I've owned a couple of HEI equipped vehicles. A 1975 GMC w/ 454 and a 1981 Eldorado. I had the truck for 15 years and never had a problem with the module. The Eldo was blowing one about every month. A close examination of the factory wiring showed a ground that was missing on the car. There was a thin metal strap in the distributor cap that was missing. Once the ground was restored it never blew another module, but it did blow a couple of transmissions. That is another story.
Exactly I eliminated blowing modules by running a separate ground from Distributor body to good engine ground. Been good for 5+ years now. Still carry a spare just in case but gladly haven’t needed it.
I've been thru the ground fix suggestion to no avail, they still last about 2 years in my 75 Corvette. I always carry a spare and have used it twice on the road.
I meant to add that I took one of these AC Delco failed modules apart once; the electronics are filled with a clear epoxy. Under a microscope I found an integrated circuit that had tiny jumpers welded to it and the other end of the leads welded to the circuitry. One of those wires was open in the middle. Looked just like a blown fuse would look. The ends of the tiny wire were round as if they were over headed. I suspect over voltage from some failed component overstressed the wire and it blew.
I had a 1976 Nova 5.7 that had 250,000 miles before the valves pounded out, it had the factory HEI module still in the distributor. At tuneup always clean and replace the white module paste under the module, lube the centrifugal weights. Then check the vacuum advance canister, along with the Cap and 8mm plug wires. Then always install a new distributor HEI Rotor and Spark plugs.
I love the gm HEI ignition system ! an upgrade with accel components never failed me ! what did fail on me was using a cheap rotor ! the carbon nub that makes contact with the center tab would burn thru and cause a misfire or no start ! and always carry a spare module ! the real beauty of gms HEI is it only needed power and rotation to operate ! chryslers had the dreaded ballist resistors i owned 2 and always kept spares in the glove box ! pretty cool channel you got ! very knowledgeable and informative !
i cannibalised my k1500 1986 for awhile and my 1970 b-bbm ran better with it. but yes on that engine all old school or new 2010-up engine management not the uncanny valley in-between the 2
Also rotor burn you check and there's no spark so you think HEI module. but don't forget that rotor look for a burn hole hard to find when it's black plastic. if you can't see try an old good wire on the center button the other end to everything connected crank it if you see spark it's the rotor for sure not the module.
@@edwardmartinez9459 the voltages are unreal ! i upgraded my 68 c10 to hei and got a mile down the road on a rainy day it started running bad ! i forgot to tighten the distributor hold down clamp ! truck was still running and i went to turn it and got knocked on my ass ! I'll never forget that ! never had a prob with hei since !
Hi Adam, just wanted to add some thoughts for clarity on the issues seen with GM's HEI modules. The original modules were white in color when they were incorporated in the familiar large-body HEI distributors in the fall of 1973 for select 1974 model year vehicles. By the fall of 1974, all passenger cars (the 1975 models) received HEI ignition systems to meet the increasing demands for Federal Emissions requirements and basically provide a "hands-off" approach to maintenance on the distributor which affects ignition timing (as anyone with points will know that regular maintenance is required) and ultimately the emissions out the tail pipes. Unfortunately, as you stated, things weren't so hands-off. The original white modules were VERY problematic. This stemmed from the fact the internal control chip designed by Motorola had an output transistor (the main switch for turning the coil on and off to generate spark) was not adequately designed to protect itself from back EMF (this is the spike that occurs when the magnetic field collapses when the power to the coil is turned off). To add to the problem, GM increased the spark plug gaps to coincide with the higher available voltages from the HEI system to ignite the leaner fuel mixtures being used by the industry at that time. The weakness in the module was exploited by these conditions. Many times not only did the module have to be replaced, but also the integrated ignition coil as a shorted module with constantly supply un-interrupted power to the coil, thus overheating and shorting out the internal windings. GM was then faced with a full on replacement campaign to change out the white HEI control modules with the more reliable black colored modules. Spark plug gaps were also closed to reduce the risk of misfire/back EMF events. The biggest issue is owners using supplied (or purchased on their own separately) silicone grease/dielectric grease/"tune-up" grease under the module. Completely WRONG. A good heat sink compound paste needs to be used. It is opaque white in appearance as the silicone stuff is clear or translucent. It is critical to provide the thermal conductivity between the bottom plate of the HEI module and the mounting pedestal in the base of the distributor with the use of the heat sink paste compound. You did hit the nail on the head with N.O.S. parts. Modern components (even genuine GM replacements) are all made off-shore and the quality is lacking. Even simple replacement points for points distributors are lacking! I've been in the electronics industry for decades and worked on cars and electronics for a long time. My classic car retains the original Delco distributor with points as I know as well as others, with electronics, it is not a matter of IF it will fail, it is WHEN it will fail.
Ah, then you should be familiar with the early Ford Duraspark ignition modules whose failure rate was so high that Ford was starting to get a bad reputation for the cars so equipped...1974 and newer. They would either stop functioning altogether or develop a "hot open" when the ignition would fail after some minutes of driving, only to work again when they cooled down. Ford improved the module circuitry on replacement modules, the upgraded ones were identified by sticker on the module which read "Motorcraft..Tested Tough" If we didnt see the sticker or a quality aftermarket module such as NAPA/Echlin or Standard Plus--we replaced it, and NOT with the Wells junk that was common in the day. These failed at least as often as the GM HEI modules, and the other problem with the GM distributor was replacement of the rotor with a cheap aftermarket unit which would often burn through in the center shorting the spark directly to the distributor shaft.
You are dead on man.......down to the RIGHT grease that goes underneath which I have seen guys do soooo many times years back.I still run 3 G.M. s with this style module installed right with quality part is and excellant design.
BTDT...You are exactly correct in every portion of the failure mode description. The original black GM modules are the only ones that are worth using as a replacement. Other aftermarket modules are junk, Pertronix included. The white thermal conductivity paste (don't use the clear grease, source the white from an electronics store) is also a key element in the reliability chain as heatsinking is absolutely necessary with these modules. It's also a good idea to tape a piece of 320 or 400 sandpaper to a piece of glass or other very flat surface and lap (rub) the metal base of the new module on the sandpaper to ensure flatness. I had one module with one of the two staked eyelets (rivets) that extended below the metal base mounting surface of the module, ensuring a terrible heat transfer surface. A SPARE IN THE GLOVE BOX, WITH TOOLS, is mandatory!
I've been using GM HEI ignition distributors on all the vintage and classic GM cars I've had over the years and have never had a failure. I use them today in both my 71 Nova SS and my 72 Buick GS (retro fit). I remember my brother had a Pontiac Grand Prix that had the module fail on the way home from picking the car up brand new from the dealer. That was the only case I was personally aware of. I was in the construction business for over 20 years and we had a large fleet of pickups, mixed Ford and Chevy's and I never recalled having an HEI failure. Actually, we were also in the snow removal business and everytime we had temps go below 0-5 degrees, a few of our Ford plow trucks wouldn't start (they were parked outdoors). We had to pull the ignition modules off the drivers side fender well and warm them up. Fixed. Maybe I was just lucky but I still rely on and have confidence in the HEI system. Mazda, Toyota and a few other foriegn makes had their modules in the distributors. My dad's Mazda MPV had a module failure in 1994 and the module was not replaceable. He had to buy an entire distributor at the tune of about $500. Ford Probes used the same ignition.
My experience is the same as yours. I have had north of 30 GM vehicles, never had a HEI fail. Didn't even know this was a thing. I upgraded numerous pre 74 to HEI. I also replaced DuraSpark modules with GM HEI.
getting good QC easy and ok cost, points or carbs based systems parts ect. in 2022 good luck i quit and moving forward with my classics ( 440bbm/hemi ) is modern engine control 2005-up as the aftermarket makes kits/diy for older generations of engines ect. but im not driving a pebble wining car ether so i see it doesn't matter as much if it's modified tastefully
The 1972 GS uses a slightly different shaped ram air bucket on the distributor side compared to the earlier models with that cool air setup. No fitment issues? I didn't use the radiator hose bracket off the t-stat housing on my '70 with the HEI, and I used an Edelbrock dual plane intake, the iron one was just so heavy. The aircleaner sat a little closer to the hood in my car but it worked just fine.
I remember the GM HEI the coil could put out 50k volts. When the plug wires would go bad and create an open circuit the spark would usually jump through the rotor and ground to the centrifugal weights, you could tell from the rust on them. Of course every now and then the current would hit the module. Game over. Thanks for covering this!
I never forget my first and only experience with a failed module back in 1997. Going 70 MPH in my 1981 Trans Am in the "fast lane" of the local interstate and cruising, suddenly the engine shut down and all the warning lights came on. I was able to shift the automatic transmission to neutral and nurse the car to the shoulder. This is an interstate with 5 lanes, mind you and it happened around 4 PM semi-rush hour. Like others have mentioned, the problem is that its failure is sudden death, and you get no advance symptoms whatsoever.
@@catsaregovernmentspies my k1500 seamed to always fail in the driveway sofar🙏🤞 after starting up and putting in gear aka stuck at the house 🏡 and easy fix vs no mans land. and yes keeping cold 50-65 f and using better tremale pastry lol from the computer 🖥geeks does help as does keeping the turning + battery/alt 👌ect.
@Logan Forney race cars do it every time. And yes, my truck has one thermo pasted to bare metal on the firewall, wired on a switch. My tach fails, I switch and Ignition!!!!!!!!! I like to street race to the speed limit in my old jalopy and patina'd 79 chevy 3/4 all-time AWD that looks like a slow one. It's overbored, sbc 400, with AFR 227, drag race cylinder heads with offset lifters prove otherwise. People will pass me at full speed when I shut down at the speed limit. I've got them until I do. I had a Honda passport really upset in a 60 zone. I left him at the light, he floored it and caught up to me at 40 mph. I floor it to 60, completely dusting him for a few seconds when I shut down and he goes peeling by me with bald tires to be pulled over with his speed being over 80 mph I'm sure! Lol Baiter!!!!! People hate that old chevy being fast at all.
@@shedred1967 as a teen-26 id have tried street racing but my old man would have strung me up by the rafters lol 😂and then i got married and the wife didn't want to be a widow and or stupid in my 68 C10 or k1500 and more so in the 1967-70 charger ( as one point we "shared that car" and mom hates that car 😂😁 i told her at 14 i was going to buy one so good luck stopping me ( By 21 i had it ) besides most of my bs was in a v6 sedan or the rusty C10 SBC-sm465 4:10fg lol 😂as the bbm charger is a 🚓magnet lol ) or her caddy pissed 😤😡 off so i limted my self to "testing parts " 😉😁 and or not breaking and laws or getting chout
@@shedred1967 is yours a stick? because at 16 my k1500 700r4 went bad and a buddy at the time was parting out is k1500 1-ton sm465 so my mom threw a fit somehow in her mind that = a 6c chevy on full kill lol 😂no way and she would have hate yours as "its a race car" nope lol
The problem with electronic ignitions, beyond the thermal/weather related issues, is that their life cycle curve is basically a cliff. Unlike points and condenser systems, they don't gradually degrade with perceptible differences in performance. They're simply on/off and as Mr. Murphy states, they fail at the worst possible time.
I've replaced at least a half dozen in the same vehicle over the years. The most recent was just last week and I got a SLIGHT warning. (not a great warning cuz I didn't realize what it was warning me of) Shut it down hot. Went to buy milk. Came back and it stuttered on startup like it was somewhat flooded. ( it NEVER does that). Drove it home and parked it no issues. Wouldn't go again. Installed spare I bought only 2 months previous. Didn't even trouble shoot it. Just prayed it wasn't a dud right out of the box like the LAST one I got at NAPA!
I've had 2 trucks with the GM HEI ignition module. A 1989 Chevy C1500 and a 1992 GMC Sierra both had the 350 (5.7L). I owned both of them since new and put over 260K miles on each one. I only had to replace the module once on each of them. Luckily, I was never stranded. My friend had a 1990 Chevy C1500 and replaced the module a few times before reaching 200K miles. It turns out he wasn't using "heat sink grease" between the module and the distributor because it didn't come with the module when he bought it. The ones I bought at Autozone didn't come with heat sink grease either but adding the heat sink grease was one of the steps in the replacement procedure in my Haynes' manual, so I bought some and put it on. I like to think the grease helped, but one thing for sure: I was lucky to get so many miles from these aftermarket modules.
As a 70's and 80's era GM tech, seems I remember replacing more failed pick up coils than modules. This issue went away when they eliminated the vacuum advance which would flex the wires on the pick up coil to the point of breaking. I still have a collection of GM pick up coil magnets on my tool box...
I've been driving GM HEI since 1976 (including in my 77 GMC Motrohome which you have referenced)and never had a module failure. You have to keep all the secondary components in good shape-- cap rotor wires and plugs and gapped correctly (.038") Any degredation in the secondary allows the coli voltage rise to increase very high before discharging. This proportionally (it's a simple windings count ratio) raises the back EMF to the module when it opens the primary circuit. They can take this for a while but not forever. Also the heat sink compund dries and shrinks after 30 years and does not provide good heat transfer. Furthermore some incorrectly use dielectric grease instead of white heatsink compound, which works but not as well..
One thing i notice when i did use dielectric grease After a year i would go back to look under ignition module,and the grease was still there.That clear grease that came with the module would almost or be gone under the module. Now i use the white heatsink grease .When i look under the module after a year it is still plentifully there.eleminating any chance of the module frying.Now to eliminate heat from the coil in cap by getting one to put on the fire wall.
Interesting to keep a spare HEI module in the glove box... kind of like 1960s-1980s Mopar owners keeping a ballast resistor in the glove box! Never really had too many problems with the HEI, but the GM "Optispark" ignition system used on the 1990s LT1 V8s was not known to be one of the most reliable, and certainly not easy to access / repair, being behind, under the water pump. As a 1996 Buick Roadmaster Estate owner with the LT1, I can attest to this.
New to your channel by the way and enjoying. I did 17 years as a GM dealership mechanic and the biggest component failure that I remember was when they went to the plastic intake manifold gaskets on V6 engines that carried coolant through the intake. The 3.1 or 3100 they may have called it and the 4.3 come to mind. This was in the 90's and Dexcool had come out too. These were 100% failure rate for coolant leaks. Coolant would leak externally and internally at the corners of the intake. It wasn't if but when. You would pull off the intake and those plastic gaskets were in pieces. I think the idea itself was as bad as the component. Felpro came out with rubber coated aluminum gaskets that were much more durable. We were paid a flat rate per job and I did so many I was making triple time on the 3100s. You could leave the rear valve cover on then use a line wrench on the rocker arms to open the valve enough to slide out the push rods and change the gaskets
My dad's last pickup was an 86 Chevy half ton, 4.3 L Vortec V6. His Chevy ate those HEI modules like candy. The V8 version was about 20 bucks at NAPA, the V6 was $100. I was working for a division of Echlin at the time and he asked if I could get some modules with an employee discount. I found out I could buy them for about 5 bucks each, so I got 3 for him. He replaced only one and that lasted for the rest of his life. When mom sold his pickup after he passed away in 1993, the other two HEI modules were in the glove box.
So I have five cars between 1965-1973. The 73 being a Dodge and the others all Ford products. All the Fords use the Pertronix II since it first came out powered through a relay. One car had a first year Pertronix I and all have performed great. However, for some reason the Dodge had trouble with the Mopar system and also blew two Pertronix II modules. I made my own HEI system for the Dodge using an NOS GM Module, a Ford e-coil, and powered through a relay. The module attaches under the Mopar distributor using the heat transfer paste. I get 13 volts to the ignition, great looking plugs, quick start, and so far am now 6 years into.
Yeah I have an HEI on my 340, runs great. Hot spark, and has zero problems with a 10.9:1 compression ratio, or 7000 rpm. I think these systems get a very bad name from GM rushing them into production too early.
Owned several GM's with HEI and only had one module go bad on me. The flaw is when the silicone dries up and the chip frys. Not a bad design when serviced right during a replacement.
I replaced replaced the ignition module on my 1985 Chevy LT-9 engine and it was original. The original mind you from 1985 still functioning in 2023. The problem was a burned rotor probably secondary to old spark plug wires. I went ahead and replaced the ignition module as well and bought a backup to keep in my glove box.
I have only once had a bad experience with Mopar Electronic Ignition System in 1972 to 1989 Rear Wheel Drive cars. It was a 1976 Dodge Aspen SE Station Wagon. Water got in and fried it. Good thing it was still under warranty at the time. The K-Car Ignition System fail point is the Electro- Magnetic Pick-up, the little wires break over time. Should change it about the same time as the Timing Belt on the 2.2 and 2.5 liter engine.
Remember these issues all so well! At our shop we also would see the Ford TFI modules and the 86-92 various GM vehicles with what insiders called "Phantom Stall". On those GM cars we would have to look at the date codes on numerous sensors (crank, cam, MAP/MAF) and replace the ones in question. The worst issue was the intermittent "stall and cranks but won't restart". By the time the car was towed to our shop the car would start right up and could be driven off the tow truck and we were "unable to duplicate the condition". Customers were pissed to say the least. My brother and I wound up doing a series in Motor Age Magazine on how we finally repaired these intermittent problematic cars. Needless to say it took a lot of hours of driving these cars with scan tools and lab scopes connected to various components trying to duplicate the stall condition and catch which electronic sensor was out of range.
Maybe because I was in Arizona and drove lots of miles I removed the Points/Condenser and installed the Pertronix electronic kit. I kept the Points/Condenser in the glove box but never had the any trouble. I finally installed a HEI from a used farm truck never had any trouble with it either. I believe everything you say because I know others had trouble so I maybe I was lucky for once.
Ford also had problems with a TFI ignition module mounted on the outside of the distributor, my 1984 Tempo had a recall, and a day before the scheduled repair mine quit and had to be towed.
my 2003 Buick lesabre ICM failed in Chihuahua, Mexico. Due to the scarce availability of parts, my mechanic here in Mexico found a used ICM at the junk yard. I will replace it when arrive in Tucson, with a new OEM. Wish me luck!
I had four Hei modules fail in a month. All standard motor products modules, bought at the local parts shack. I got a Davis module off summit, no problems since.
My '88 XJS V12 HE has a GM HEI module located inside the AMP which is mounted on the driver's side intake manifold. That HEI module is, by far, the biggest problem I have w/the car. I always keep an extra AMP and an extra HEI module (along w/tools) in my trunk. I have had modules last for as long as 2 years, while the last two I had both lasted less than 2 hrs. Prices have doubled in the last couple years (although still around $50), but it's really the issue of just shutting down somewhere out on the road that sucks....sure wish I could find an alternative.
I worked for Autozone for almost twenty Years, this part was a Hugh seller and I have tested hundreds of these, the aftermarket does have some problems for quaulity....
Just had to replace ignition modual in a 3 week old Accel HEI. Car died while driving 3 days ago and just fixed it now Was driving me nuts because no one has a video on how to trouble shoot modual. Tested everthing else and all good. Watched 2 vids on bad modual so I said screw it spent another $50 bucks on Petronix Flame unit and started right up. Thanks.
Little known fact. Later air-cooled Porsche and triumph (Lucas electronic ignition) used this module but in a firewall mounted box. If you need the Lucas part, it'll cost you $150 the Porsche part $400+ or you can remove the rear cover and just replace the module in the case for $30.
I had a 1994 Chevy truck with the 4.3 V6 that had that system and after replacing the distributor cap a d rotor my truck would not start. I replaced the ignition module it ran fine. I surmised replacing the rotor which was stuck in place so I had to bang and ultimately break the plastic rotor it made the ignition module fail. The new module had grease you had to put under it or it would cause the new module to overheat and fail.
Another homerun video! When I bought my very low mileage '76 Coupe DeVille back in 2002, I read about some of the horror stories of this module. Even though the car ran great, I went ahead and changed out the module with a new one as insurance. I think it was an aftermarket brand though. Regardless, the car is still running great today. I really enjoy your videos and always look forward to the next one!
I would suspect that many failures were due to improper paste installation as well. And, I'm sure build quality degraded over the years as this system was changed and quality was forgotten about.
Hello Adam, nice explanation. In my former spare parts selling job back in the 80's and mid 90`s, the electronic ingnitions systems were a tricky stuff for all old school mechanics who believed that contact points were the real deal. No way, the electronic ignition was something positive devices for the automotive industry, thanks to Mopar, the very first one to featured such an element. The heat inside the distributor probably caused over heating component isolating the power supply, so fot my personal experience, the Mopar system was superior over the GM H.E.I one as I could see over the years, because the Ignition External Module from Mopar did not suffer for heat or humidity, because was an external fitting unit, almost placed above the inner fender dust skirt or over the fire wall. In my Chevy Celebrity I owned some years ago, and with almost over 162.000 miles. that module was the original Delco Remy factory unit!!, believe me, but was little different, with 4 or 5 contact tips rather than your 4 contact module, 1875990 GM catalog part number. They were cheaper to buy, in many brands, such as Wells, Standard, Valley Forge, General, United among many others as well, keeping a higher price for the Delco Remy unit. But to be fair and serious, the HEI ignition GM system is a world class design, very dependable, long lasting performance. Thanks for the info, very ilustrative. Salute, from Bogota, Colombia. Take care, man.
Mopars of the '60s and '70s used a 'power' resistor in series with primary coil circuit to drop the input voltage to 6V after startin g the engine. What happens is: that HOT resistor gets hit with rain water, causing the part to crack resulting in engine shutdown! The engine will start normally, but will shut off as soon as you release the ignition switch!
My 76 Nova went out in the mid 80's but I was lucky enough that it only failed when it was cold, once I took it off and warmed it up with a hair dryer and reinstall it the thing would work fine until the car again sat for 8 hours or so. It took me a few days to secure a new one so I got pretty good at pulling things apart.
I have converted two Corvettes, a 350 ci and 454 ci over to HEI ignition during engine replacements, one in a 1965 Corvette and one in a 1968 Corvette. Both have been working fine for over 35 years. Had to replace several caps and rotors, but I have never yet had to replace a coil or ignition module. Don't know why you are having all these problems, but I have not.
The competing Ford Duraspark system had issues too, they used a single low gain transistor, which required high current in the driver circuits with big hot ceramic resistors, which generated heat and the thermal cycles would degrade the circuit board connections. some of the better aftermarket modules (Wells) had a Darlington transistor for more gain and had driver circuits that didn’t produce so much heat.
I have a 65 El Camino,350,th350. My issue is : I could be driving,or at an idle at a light,and it will die, loose all electrical power,I turn ignition switch off,put it neutral,turn the key,and starts right up...any clue why this is ? Help Thx....Amy
It typically last around 20 years before corrosion takes it out. The failed modules usually have green electrical corrosion inside on the contacts where they connect to the circuit board. It's actually a well made well insulated part as the module circuit board is covered in heavy silicone epoxy so it resist moisture and corrosion for possibly decades. Usually when they give out, the car will restart in a few hours then conk back out again when the module overheats. I've only had one fail on me but the car was 22 years old at the time and had 145,000mi on it. Possible symptom of it going bad are low struggling acceleration in hot or damp weather.
I had one problem with that module. It was in a late 1970s Chevy 305. I replaced it and it ran to being disposed of because the rings were shot. The HEI ignition was wonderful. I never understood why the spec was 35 thou for the plugs. I increased it to 55 thou and that increased the power dramatically. An old mechanic suggested 55 thou. All of my other cars and friends cars I did that to and everyone was happy about it. That car went from 15 MPG to 18 consistently. Points - love them while you have them. Friends that I know that still use points tell me that the quality of them are going to crap. One guy does racing in a Porsche. He had to break down and switch to electronic because he couldn't buy points that would work anymore. They're dying out. The only place that I know still uses them are prop aircraft. They have self contained magnetos. Two of them. Some old tractors have Bendix mags as well.
Ford 7.3 power stroke Crank Position Sensor. Most of us owners keep a spare in the glove box and a ratchet,. The gray one now to my knowledge is the last revision. Oh and the fuel bowl heater. I think it’s fuse #12, also causes a no start condition. Pretty common.
My mother's 1978 Chev Monza with the Iron Duke 4. Went through several of these, left her stranded a few times. Knew to let it cool and then would work. Warranty replaced about 3-4 of these. This was the 1/2 moon 4 connector type, I replaced most of them myself. Used the gel as directed. Finally after these 3-4 replacements got one that worked for more than a few weeks.
Adam: Always appreciate your point of view and understand that you are not a big fan of the early attempts at electronic ignition and fuel systems. GM's HEI, variable venturi carburetors, electronic Rochester carbs, and arguably the worst of all... Chrysler's Lean-burn! They were all plagued with teething problems, and the parts available now are ancient IF you can find them. However... you have what 30 or 40 cars? None are driven more than a few miles per year. Rebuild a carb and distributor and the car will stay in tune for a decade if you treat it to a trickle charger and some Sta-bil. Personally, I like modern systems MUCH better. Nine years, zero fuel or ignition system maintenance, original plugs, one new battery. Starts every time and runs like new!
I purchased a brand new in 1987 a C-10 short bed pickup with a V6 4 speed that I loved until I broke down because of this module. The second time it broke down I had the module changed again and traded the truck in for a ‘90 3/4 ton Scottsdale with a 350. I wish I kept the truck looking back now.
I have a 1979 C-50 with the small block and an MSD HEI billet distributor on it, and it’s being doing dumptruck work for close to 2000 engine hours now on the same entire distributor.
I hate to admit you're right about points, but my 89 Accord has been dead in my yard for the last few years because I can't find a working ICM or pickup coil for it.
I remember back in the '90s paying a Chevy dealer for a new HEI module, thinking it would be better quality than aftermarket. Maybe it was. Imagine my 'surprise' when I opened the Delco box to find 'Hong Kong' on the bottom of the new module! Even worse were those GM HEI distributors with vacuum-advance. A wire to the captive pickup-coil would break. Then you would need to pull the distributor, drive the pin from the gear, drive off the gear, drive the shaft from the housing, etc.... Worst of the worst was the HEI on a Chevette with AC. It used the same massive HEI ignition-coil-in-cap unit as a V8, but with only 4 plug-wires. You couldn't do anything without first pulling the AC compressor AND its' bracket. Then, if you needed to remove the distributor, the fuel-pump ran off a cam on the distributor-shaft, so the pump had to come out too!
Good Video. Had a 81 Chevy Citation Duke engine that modules fail in hot AND cold weather…32 degrees. Also distributer gear that year changed to plastic/nylon. Only car that stranded me 3 times, and I tried to maintain it like an airplane.
I had the same problem. What I learned is not to use the clear gel it is water based and will evaporate and dry sooner and module will over heat not start when engine is hot on hot summer days. Engine cools off and will start. Use the white paste with silver in it for all computers if you can find it.
The distributor on my 1975 chevrolet truck finally failed last July. Don't know exactly what failed, but it was burning hot. I was amazed that an original component (excluding the rotor, wires, distributor cap) could last that long. An original GM replacement cost less than $100.00.
All experience is personal. I doubt you have owned a vehicle with Lucas points based ignition, but these were awful whereas in the last 40 years I have owned 13 cars, bikes and trucks with electronic ignition without ignition problems. My last experience with points was on a group climbing trip to Mexico where a VW camper would not start. The owner was perplexed because he had just laid out a lot of cash on an extensive service. I fished out a plug and found no spark. Opening the distributor and removing the rotor, the points were shut because of a loose locking screw. Using a thumb nail in lieu of a feeler gauge, I reset them and it fired up.
An even bigger headache although not as frequent was the pole piece wires breaking off which then required the removal and complete disassembly of the distributor. yuk. Frankly, while I did always keep a spare I didn't have many of the modules fail.
You're the first person I ever ran across that said the GM HEI modules aren't very reliable, but I guess it's good to listen to all viewpoints. I would buy a replacement module from Pertronix or Performance Distributors.
My mom's 88 Chevy Celebrity died on me without warning. I was young and knew nothing about cars. Luckily my friend's dad knew what it was and showed me how to change it. After that I started learning as much as possible about cars. Now I fix everything myself. So thanks GM. If not for being stranded by a bad component placement, I might not have been interested enough to learn about cars. Now I work at a collision repair/body shop.
I worked in GM garages from 79 -88. The early HEI modules had issues but from like 78 on they were quite dependable. The biggest culprit I found were aftermarket rotors not working. You needed to use a white GM rotor. Black or blue ones would fail right out of the box. You need to do a video on Chrysler ballast resistors. Talk about leaving people stranded!
It sure is critical! So are lots of components, fuel pumps come to mind as an example. These modules indeed had there issues but so did the pick up coil, I’d say this is a larger problem and indeed I replaced more of them than modules. Your point that you need tools to change the module being a problem is true but the pickup coil requires removal of the distributor completely to replace. So yes this part can fail more than other makes and types but I’ve put lots of those on the fender ford modules. I would think statistically the failure rate would be very low compared to units installed and total mileage. Unfortunately you seem to be the statistic, lol. Poor product and the lack of paste contribute to the bad rep. Great info as always! Ps. I also have run a “unitized” gm on my 455 Pontiac which is the only engine I believe it was available on. 72-74. Sort of a test bed for the hei. Daddy to it I guess with the transistorized being grandpa. Anyway it is original untouched other than the secondary harness and is north of 160000 miles. Worst part ever?? Idk but that sudden wtf when it dies on you,, sure makes you think so. Jim.
The Olds V8's I'd say '75-'77 had .080" spark plug gaps to fire lean idle mixture. This lead to the "rotor" burning a hole to centrifugal advance. Also the plug wire terminal closest to a coil mounting screw would burn through the plastic causing a dead miss on that cylinder. Another issue was rust would lock up the centrifugal advance. That lead to removing distributor taking it all apart glass beading the advance and greasing the reluctor on the shaft. Also the nylon bushings on the weights would fall apart. Thexton at that era had a kit to install new improved bushings on the weights. There's no telling how many HEI's I rebuilt in that time. Oh I might add on the Olds. We'd knock the plugs out of the carb to richen idle mixture and install .035" gap spark plugs.Happy customer. In addition while the distributor was apart a new GM pick-coil was installed. The white and green leads would break caused by action of vacuum advance.
Thanks for the informational video. I couldn't start my car yesterday, but it fires up and is running today. Is there a test for the module or do I just replace and be done with it?
I built a very good HEI system for my 65 Galaxie 394 .20 over FE. I got a TFI heat sink and attached the4 pin module and mounted it on the fender well. I got the one my circle track buddy’s use with the gel. I have used this on 4 different vehicles. If someone is stuck and I just pull it off and help them get it home, put it right back on with my own looms that hook right to the factory distributor. I also have a 1996 F150 remote mounted coil mounted on the power steering bracket, in common is they have great air circulation and run cool. The secret is a well grounded heat sink, a weather packed loom and air circulation. They live forever. If you do have to get a module, go to O’Riellys and get one for a Cadillac 500, or a 454 heavy duty truck. I have pile of good ones I got at the junkyard all bagged and tagged in my closet in the house for temp and moisture control. I have not had a blown anything running 30 amp relays to all loaded circuits. My ignition is a nice hot 52,000 v and runs at alternator regulator voltage which is 12.7 volts. I plan to add an 870 DP with annular primary boosters and a VS7875 turbocharger with a blow though boost referenced fuel system and hat and a referenced dial a jet on the secondaries. 61, retired but hoping for 750 hp at the rear tires .
A nice talk about electrical components on a cars , GM. I had an 87 Dodge D150 pickup with an 318 V8. I always keep Ed a spare ballast resister and voltage regulator in the glove box. I had to replace the regulator twice and the ballast resister once.
A buddy of mine was giving me and a complete motor a ride to have it installed in my car. 20 miles from destination the HEI ignition module died , fortunately we had a spare in the back of his truck . Now I always carry a spare in the glovebox.
I retired as a auto mechanic about 15 years ago. In my bottom drawer are a box of Chrysler Ballast resisters, GM HEI modules and Ford Thick Film Modules.
The GM HEI units were substantially more reliable than the Ford units of the same era. I went so far as to mount a second module on the fender well of my 79 Ford truck just in case the operating unit failed. This eliminated the need to rifle around in my tool box looking for a new one on the side of the road. I would simply plug it in to the new unit. 3 times in 3 years. I never had a factory GM module fail. As a rule I replace the module along with the cap and rotor at tune up time. Easy to change and not expensive to purchase. The aftermarket modules are junk, especially Petronics.
It's kind of neat with a Ford ignition modules when they overheated, you could pour cool water on it and wait a few minutes and it will start right back up generally. Granted, you'll have to stop again when it overheats again before you replace it. But you certainly couldn't do that with the HEI in general motors. I guess I got lucky I never had a problem with any of mine. But I certainly see his point
I had an 84 Pontiac Grand Prix that never had any ignition issues and I owned that car about 15 years. I think it was the early years of these systems from 1975-1980 that had the most trouble.
Adam, appreciate the good content once again. You’ve mentioned more than once that you’ve found aftermarket parts to be inferior to OE. I’d like to address that. Disclaimer, my career was almost entirely in the parts aftermarket. Surprisingly, I’m going to conditionally agree with you. When I started in the aftermarket in the late ‘70’s/early 80’s, aftermarket parts were quite often superior to OE parts. The aftermarket had the advantage of “reverse engineering” OE parts, particularly failed OE parts, and gaining understanding of what caused the failures, and create more robust replacement parts that solve problems. However, the technological revolution that occurred throughout the 1980’s and 1990’s made many parts much more expensive, and diagnostics much more difficult thus costly. Consumers began to push back on the cost of automotive service, service providers pushed back on parts suppliers, who pushed back on manufacturers. To cut costs, manufacturers would cut expenses in manufacturing or source parts from low cost providers. There are still brands in the aftermarket that don’t succumb to this pressure and offer high quality parts, even parts that fix OE problems. A good rule of thumb is the old adage, “you get what you pay for”. There’s a chance that a low cost part, when price is compared to an OE brand or known high quality aftermarket part, may have some deficiencies in quality that will disappoint in performance or durability. While this may not ALWAYS be true, proceed with caution on low cost parts.
So if you've got a car with an aging HEI distributor, what do you suggest to get it good as new, rebuild or are there good quality replacements available?
My first ever vehicle was a 1994 lowered C1500 (Still have it) and the Accel Ignition module behind the cap decided to have a stroke while I was driving and it instantly shut off. Back then, I wasn't as knowledgeable as I am now about C/K series trucks so, I literally had a panic attack on the side of the road. Lol, my father is an expert mechanic and helped me fix it.
I also worked at a Napa store for 10 years. Think I sold 1 HEI module. Sold dozens of Ford Modules Part # TP32. Also had a Chevy wagon in the shop once that had most of the distributor cap missing and it still ran!
Good advice Adam on the HEI. My Chevelle had an old MSD electronic ignition and I debated putting an HEI in it instead since the MSD was failing intermittently, yes leaving me stranded a few times! It was tough to troubleshoot since MSD kept saying their ignitions don’t fail intermittently. Not true! Long story, I ended up getting a new MSD, so far after one year no issues.
Hi, great story. I am based in Australia and our local GM's are called GMH. We had point is GMH until 1982 ( strange as local chryslers got them 1973 and ford 1978/1979 ) We used the same bosch 4 pin model you should, however as ours was basically same 6cly from 1964 and same V8's from 1967 we also used the same distributor and what the factory done was added a metal "shield / plate" on the lower distributor body and mount the hei module on that metal plate A short 4 pin wiring harness went into the lower distributor metal body - while the distributor was basically the same and electronic internals instead of points they did get a larger diameter cap and rotor to stop the arcing between each lead terminal in the underside of the distributor cap Now these ran great for 5 to 10 years then the problems emerged, originally with V8's as the lower distributor housing is shorter and mounted basically rear engine like a gen 1 chev 350 / mopar small block Plus the module was in the rear so it was a pain, to note the rotor position, remove the distributor and work on the plate, new module would work 6 to 12 months then the same problem - the importance of the thermal paste was basically unknown and many people did not clean the surface and re apply the thermal paste 6 cylinders were actually OK as they were on less vibration engine, not driven as hard and the module faced east west with plenty of clear fresh air and not much water - there problem was being parked outside and the metal plate would tarnish and thus bad conductivity between module and plate A trick everyone had was throw a bottle of water over the module if it starts it was hot and you can run the car for another 30 mins / few days - if it did not start it and it was a hot day it was probably fuel vapour lock - another problem as we did not have fuel pump return lines on mechanical fuel pumps I had a issue with my car, the sparky was busy and he said " can you fix it yourself" i say NO, he said can you use hand tools, i said YES - so he spent 1 minute telling me what to do, i removed the dizzy, took of the module, took of the wiring harness, used a hand file and sandpaper on the mounting plate, applied the paste and bolted on a new module - reinstall the dizzy and he got me to look where the dizzy was now and rewired the firing order from there - turn the key - bang it fires up He just charged me the counter price for the module - and said if i have a problem come back, if the car runs hot ( as it was a V8 and the commodore has a cramped engine bay ) i can come back and he will do a mod, i told him i would see him next week and the car had messy under dash wiring due to a prior owner being a butcher and a radio install, he said if i promise to come back he would order the nder dash harness from GMH and help me out I week later i turned up he had the harness and i was simple to removed from the fuse box power and use the new speaker wiring, he asked about the HEI and i said fine, and he said we will do the mod - it was simple, it was a simple rectangle hollow box section of aluminum - he had a few 6 foot lengths of it, he chopped of about 4 inches of it, ran a large screw into the firewall and mounted the alloy then grabed a premade 4 pin extension harness he had and with new thermal paste moved the bole from the dizzy to the firewall, the hollow box section had better thermal conductivity plus being hollow and on the firewall was no more vibration of the engine. That worked for the 8 to 10 years i kept the car, he also had some mopars and used that module instead of the factory ECU The secret was simple use genuine bosch component, keep them as cool and vibration free as possible
I had a couple go bad on me, and yes, the original GM component is a much more solid state. I always keep a dual point distributor in the back seat just in case. The points never wear out when the dwell is set perfect, and GM makes it easy to set while running. Also, never buy a Mallory brand HEI. Their reluctor is thin and fragile. I've had two fails, both in winter. Never again. My Mallory points and their unilite strobe have never failed me, ever. I won't touch their HEI until that reluctor is addressed. Accel, MSD, or Progression Ignition all day, every day when it comes to HEI. My stock replacement Accel distributor even makes more power than my old Mallory performance HEI on the dyno. I was surprised again, though the module went out three months later.
I have never had a GM HEI module fail in any of the dozen or so GM vehicles we have owned that used them. However, I always placed generous amounts of electronic-grade heat sink grease between them and the distributor bodies as soon as I could after purchasing the vehicles because I was aware that they ran hot. On the flip side, I ended up donating a Ford truck that ate firewall-mounted ignition modules on a regular basis because I became so sick and tired of dealing with them. And I had an MSD 6A module on my last truck (K1500 Chevy) that stranded me on several occasions. I would be driving along happily and then sudden silence with no restart and absolutely no prior warning. It got so bad that I carried a spare MSD box (despite the cost $$$) before I gave up using them completely..!
Had one fail on my 1991 Chevrolet Silverado. Turned into a real mystery finding the problem. Turned out to be the dielectric grease, or heatsink compound had degraded in turn overheating the module, the grease was there to prevent overheating the module, when the module was cool the truck ran fine. As soon as the module overheated the truck would stall and refuse to start until the module cooled back down.. I replaced the module and installed better module grease, heatsink grease and never experience the problem again..
Hey!! I have really been enjoying your channel. I just wanted to comment I have run quite a few vehicles with HEI and never had the module fail (including my 84 K10 which I've owned for 22 years). Maybe I'm just lucky. But I have had to replace the module in my 93 S10 Blazer four times in the past 11 years. I agree that new parts store electronics aren't as good as NOS. And I owned an older air-cooled Volkswagen that was notorious for eating points. Keep up the great work and thank you.
I had a 82 olds cutlass supreme with that module it was a V6 I had it replaced at least 3 or 4 times it didn't seem to make any difference if they used the jell or not
Thanks for the info. I am working on a GM HEI, and at this point, I have had a great deal of trouble with timing the car. The timing mark is basically, all over the place with a variation of about 10 degrees. How should I fix it, I wonder? I'll work on that and possibly send some information which I've learned to you. Wish me luck!
I agree with keeping original points ignition in a car. I have 4 of them, they all run great. You just have to understand them and keep them in tune. Won't leave you stranded if you do that. I'm a career mechanic with my own shop but I started as a mechanic in a GM dealership in 1991. We were never short of work let's put it that way. The early port injected engines had poor driveability. GM actually had a "tap test" where you tapped on the Mass airflow sensor or the ECM with the handle of a screwdriver with engine running. If it stalled the component was bad. The problems were from stem to stern with quad 4 head gaskets, 440 transmissions, nylon timing gears, engine leaks, steering racks would lose assist, driveability issues. They put a longer dipstick in the 2.5 to reduce oil capacity to 3 quarts. Then they would run out of oil and throw a rod through the block. Those had loud timing gears too. We figured out how to change those in the car. You were supposed to pull the engine and remove the camshaft because it was a press fit gear but we would cut the old gear then tap threads into the end of the cam to press on the new gear. And that's the tip of the iceberg. I actually loved it because you became a great mechanic with so much to figure out and repair.
@@RareClassicCars You would run a nut up the bolt first then a big washer. Warm up the center of the gear. Then thread the bolt into the cam and run the nut and washer down the bolt against the gear to press it on.
I couldn't disagree more with your assertion that the GM electronic modules are one of the worst components in the auto industry. Leaving a person stranded was far less likely to happen with an ignition module than the "good ol' points" system. Points systems are in CONSTANT failure mode as the rubbing blocks wear, condensers fail, points arc and corrode, etc. After-market replacements were and are often cheap imitations of the originals, so you can't bash an OEM part for that failure. I worked as a mechanic at a GM dealership and can't recall ever replacing a failed ignition module. I drove a late 70's Ford and at the very least, had to annually replace the failed 'brain box' mounted on the inner fender. Ford's electronic ignition was much more failure prone than GM's, and let's not even discuss the Mopar junk that was mounted to the air cleaner - that system was NEVER any good. Age is not an asset to electronics so if you're asserting that the original parts are currently failing on low mileage cars from that era, then that's not even a viable argument. Replacing a GM ignition module is a quick operation, one that takes much less time than replacing and setting points.
A preventative measure is to refresh the compound between the module and the mount, and flat file the mounting faces. The white Goo never provided is "Super Lube #98003 Silicone Heat Sink Compound" (made in USA). The replacements come with dielectric silicone grease that although is not inhibitive to heat transfer, does not enhance heat transfer either. Such usage is to prevent water ingress and corrosion only. Do not use compound meant for computer CPU's because the stuff goes bad sitting for 3 years or while in use for 5 years (such as a great Noctua Brand paste). The Super lube stuff seems to last a looooong time (decades easy), and is what you find on everything (MOSFETS, etc...) Zinc oxide in the product makes the silicone transfer heat better. Unfortunately I have not found anything with a better heat transfer ability that has the extended service of the plain white Super Lube stuff. On my ford I modified the distributor mounted TFI or TFI-IV (Thick Film Integrated Ignition) module to a later designed fender mounted module. (EEC-IV) I'm working on a video documenting the mod. Ill try and remember add it to the comment when finished.
If you look on my channel, you can see I made an ignition system on my car using COP and it didn't improve reliability. I was surprised at first, basically there are many arguments going for it, and it still might, but long story short, what I learned from it are: 1. New isn't always better (the allowed dwell times were really low, lower than on the single coil on the old system that had to do all the cylinders!) 2. Coils on a heat cycling and vibrating place last shorter. 3. IGBT transistors on heat cycling and vibrating places last even shorter (best have the IGBT pack located somewhere further away from the engine) 4. IGBT driver circuitry inside the COP's is even worse, best halfway solution might be to put just coils in the COP's and let the drive circuitry and IGBT 'amplifier' sit somewhere less shaky and less hot.
I had a 1980 Bonneville Brougham coupe where this issue with the faulty module reared it’s ugly head a few times. I was 17 at the time and had no idea what the issue was. I called my father, told him what was happening. It took him all of 3 seconds to nail down what the problem was. Fond memories now.
Let's do one together on the early GM cable driven window regulators that was my bread and butter throughout the first decade of the 2000s. Grand Am, Alero, Intrigue, LeSabra, and so on.
Or go back further to the plastic tape window regulators. We had tape in bulk rolls and were required to replace the only tape. Ridiculous!! Funny how, now we almost never do electric regulator repairs on the newer stuff. my paycheck is hurting.
I’ve never had the problem with a GM car. But I have seen numerous Chrysler products that did. To be fair this was early electronic ignition and they are certainly better. On GM cars I replaced the original equipment with Accel units and never had one fail. Fiat used the same GM module and had few problems possibly because they mounted it on the inner fender. A few years ago I had a sailboat with a gas engine with points & condenser. It quit a mile or two from the marina. With a following wind of about 12 - 15 knots I had little problem getting there after raising the sails. But being the only responsible adult aboard that knew how to sail and the wind increasing to about 20 knots the problem was how to slow down. Taking my hands off the tiller resulted in a very wild spin but with one hand on the tiller and the other to drop the sails I got it into port after hitting the dock. The boat got away from me while trying to tie up by breaking the lines and I ran and jumped aboard. A power boater towed me in. I vowed right then to NEVER trust points & condenser again.
If you ever worked on a Ford DuraSpark you will appreciate the GM HEI module. I have owned northward of 30 GM vehicles and never had an HEI module fail. I have upgraded Fords and GM points to HEI and resolved the issues.
Yes, I have had my 1976 ElCamino for 30 years and have had 2 faiures, one where the car would not restart after shut off and recently had a misfire with lack of power and hesitation only under low speed acceleration and suddenly disappeared, I immediately replaced the ignition module and never had any repeat. Also as you say the aftermarket Chinese modules are notoriously unreliable for voltage regulators also. I bought a new rebuilt GM the cheapest one O'Reily's sold and two failed on the second restart, after jumping the regulars I found the regulators defective. I returned the second one and refused a third one of that brand line. I said I need a better quality unit and they said I could buy a better brand, and I said I will not pay the difference. They gave me a lifetime unit at no additional cost.
I've owned a couple of HEI equipped vehicles. A 1975 GMC w/ 454 and a 1981 Eldorado. I had the truck for 15 years and never had a problem with the module. The Eldo was blowing one about every month. A close examination of the factory wiring showed a ground that was missing on the car. There was a thin metal strap in the distributor cap that was missing. Once the ground was restored it never blew another module, but it did blow a couple of transmissions. That is another story.
Exactly I eliminated blowing modules by running a separate ground from Distributor body to good engine ground. Been good for 5+ years now. Still carry a spare just in case but gladly haven’t needed it.
@@warricksmith2640 wow are you serious that's pretty hilarious, they could have actually prevented the problem had they build it better.
@@warricksmith2640 and I don't even mean the part itself, just the ground!!!
I've been thru the ground fix suggestion to no avail, they still last about 2 years in my 75 Corvette. I always carry a spare and have used it twice on the road.
I meant to add that I took one of these AC Delco failed modules apart once; the electronics are filled with a clear epoxy. Under a microscope I found an integrated circuit that had tiny jumpers welded to it and the other end of the leads welded to the circuitry. One of those wires was open in the middle. Looked just like a blown fuse would look. The ends of the tiny wire were round as if they were over headed. I suspect over voltage from some failed component overstressed the wire and it blew.
I had a 1976 Nova 5.7 that had 250,000 miles before the valves pounded out, it had the factory HEI module still in the distributor. At tuneup always clean and replace the white module paste under the module, lube the centrifugal weights. Then check the vacuum advance canister, along with the Cap and 8mm plug wires. Then always install a new distributor HEI Rotor and Spark plugs.
If you take care of your machine it will take care of you.
I love the gm HEI ignition system ! an upgrade with accel components never failed me ! what did fail on me was using a cheap rotor ! the carbon nub that makes contact with the center tab would burn thru and cause a misfire or no start ! and always carry a spare module ! the real beauty of gms HEI is it only needed power and rotation to operate ! chryslers had the dreaded ballist resistors i owned 2 and always kept spares in the glove box ! pretty cool channel you got ! very knowledgeable and informative !
i cannibalised my k1500 1986 for awhile and my 1970 b-bbm ran better with it. but yes on that engine all old school or new 2010-up engine management not the uncanny valley in-between the 2
!
Anybody saying it's not a good system I disagree.
Also rotor burn you check and there's no spark so you think HEI module. but don't forget that rotor look for a burn hole hard to find when it's black plastic. if you can't see try an old good wire on the center button the other end to everything connected crank it if you see spark it's the rotor for sure not the module.
@@edwardmartinez9459 the voltages are unreal ! i upgraded my 68 c10 to hei and got a mile down the road on a rainy day it started running bad ! i forgot to tighten the distributor hold down clamp ! truck was still running and i went to turn it and got knocked on my ass ! I'll never forget that ! never had a prob with hei since !
Hi Adam, just wanted to add some thoughts for clarity on the issues seen with GM's HEI modules. The original modules were white in color when they were incorporated in the familiar large-body HEI distributors in the fall of 1973 for select 1974 model year vehicles. By the fall of 1974, all passenger cars (the 1975 models) received HEI ignition systems to meet the increasing demands for Federal Emissions requirements and basically provide a "hands-off" approach to maintenance on the distributor which affects ignition timing (as anyone with points will know that regular maintenance is required) and ultimately the emissions out the tail pipes. Unfortunately, as you stated, things weren't so hands-off. The original white modules were VERY problematic. This stemmed from the fact the internal control chip designed by Motorola had an output transistor (the main switch for turning the coil on and off to generate spark) was not adequately designed to protect itself from back EMF (this is the spike that occurs when the magnetic field collapses when the power to the coil is turned off). To add to the problem, GM increased the spark plug gaps to coincide with the higher available voltages from the HEI system to ignite the leaner fuel mixtures being used by the industry at that time. The weakness in the module was exploited by these conditions. Many times not only did the module have to be replaced, but also the integrated ignition coil as a shorted module with constantly supply un-interrupted power to the coil, thus overheating and shorting out the internal windings. GM was then faced with a full on replacement campaign to change out the white HEI control modules with the more reliable black colored modules. Spark plug gaps were also closed to reduce the risk of misfire/back EMF events.
The biggest issue is owners using supplied (or purchased on their own separately) silicone grease/dielectric grease/"tune-up" grease under the module. Completely WRONG. A good heat sink compound paste needs to be used. It is opaque white in appearance as the silicone stuff is clear or translucent. It is critical to provide the thermal conductivity between the bottom plate of the HEI module and the mounting pedestal in the base of the distributor with the use of the heat sink paste compound.
You did hit the nail on the head with N.O.S. parts. Modern components (even genuine GM replacements) are all made off-shore and the quality is lacking. Even simple replacement points for points distributors are lacking!
I've been in the electronics industry for decades and worked on cars and electronics for a long time. My classic car retains the original Delco distributor with points as I know as well as others, with electronics, it is not a matter of IF it will fail, it is WHEN it will fail.
Ah, then you should be familiar with the early Ford Duraspark ignition modules whose failure rate was so high that Ford was starting to get a bad reputation for the cars so equipped...1974 and newer. They would either stop functioning altogether or develop a "hot open" when the ignition would fail after some minutes of driving, only to work again when they cooled down.
Ford improved the module circuitry on replacement modules, the upgraded ones were identified by sticker on the module which read "Motorcraft..Tested Tough" If we didnt see the sticker or a quality aftermarket module such as NAPA/Echlin or Standard Plus--we replaced it, and NOT with the Wells junk that was common in the day.
These failed at least as often as the GM HEI modules, and the other problem with the GM distributor was replacement of the rotor with a cheap aftermarket unit which would often burn through in the center shorting the spark directly to the distributor shaft.
You are dead on man.......down to the RIGHT grease that goes underneath which I have seen guys do soooo many times years back.I still run 3 G.M. s with this style module installed right with quality part is and excellant design.
Your last two paragraphs sound like good reasons to swap-in an MSD distributor. [:\
@@pancudowny Unfortunately, MSD is not as good as it once was. They have issues now too. A lot of this stuff is now made in China and it's all crap.
BTDT...You are exactly correct in every portion of the failure mode description. The original black GM modules are the only ones that are worth using as a replacement. Other aftermarket modules are junk, Pertronix included. The white thermal conductivity paste (don't use the clear grease, source the white from an electronics store) is also a key element in the reliability chain as heatsinking is absolutely necessary with these modules. It's also a good idea to tape a piece of 320 or 400 sandpaper to a piece of glass or other very flat surface and lap (rub) the metal base of the new module on the sandpaper to ensure flatness. I had one module with one of the two staked eyelets (rivets) that extended below the metal base mounting surface of the module, ensuring a terrible heat transfer surface. A SPARE IN THE GLOVE BOX, WITH TOOLS, is mandatory!
This is a very good series idea. A lot of people talk about engines and transmissions, not so much about individual commonly shared components.
Hei was a huge upgrade from points
I've been using GM HEI ignition distributors on all the vintage and classic GM cars I've had over the years and have never had a failure. I use them today in both my 71 Nova SS and my 72 Buick GS (retro fit). I remember my brother had a Pontiac Grand Prix that had the module fail on the way home from picking the car up brand new from the dealer. That was the only case I was personally aware of. I was in the construction business for over 20 years and we had a large fleet of pickups, mixed Ford and Chevy's and I never recalled having an HEI failure. Actually, we were also in the snow removal business and everytime we had temps go below 0-5 degrees, a few of our Ford plow trucks wouldn't start (they were parked outdoors). We had to pull the ignition modules off the drivers side fender well and warm them up. Fixed. Maybe I was just lucky but I still rely on and have confidence in the HEI system. Mazda, Toyota and a few other foriegn makes had their modules in the distributors. My dad's Mazda MPV had a module failure in 1994 and the module was not replaceable. He had to buy an entire distributor at the tune of about $500. Ford Probes used the same ignition.
My experience is the same as yours. I have had north of 30 GM vehicles, never had a HEI fail. Didn't even know this was a thing. I upgraded numerous pre 74 to HEI. I also replaced DuraSpark modules with GM HEI.
getting good QC easy and ok cost, points or carbs based systems parts ect. in 2022 good luck i quit and moving forward with my classics ( 440bbm/hemi ) is modern engine control 2005-up as the aftermarket makes kits/diy for older generations of engines ect. but im not driving a pebble wining car ether so i see it doesn't matter as much if it's modified tastefully
The 1972 GS uses a slightly different shaped ram air bucket on the distributor side compared to the earlier models with that cool air setup. No fitment issues? I didn't use the radiator hose bracket off the t-stat housing on my '70 with the HEI, and I used an Edelbrock dual plane intake, the iron one was just so heavy. The aircleaner sat a little closer to the hood in my car but it worked just fine.
I remember the GM HEI the coil could put out 50k volts. When the plug wires would go bad and create an open circuit the spark would usually jump through the rotor and ground to the centrifugal weights, you could tell from the rust on them. Of course every now and then the current would hit the module. Game over. Thanks for covering this!
I never forget my first and only experience with a failed module back in 1997. Going 70 MPH in my 1981 Trans Am in the "fast lane" of the local interstate and cruising, suddenly the engine shut down and all the warning lights came on. I was able to shift the automatic transmission to neutral and nurse the car to the shoulder. This is an interstate with 5 lanes, mind you and it happened around 4 PM semi-rush hour. Like others have mentioned, the problem is that its failure is sudden death, and you get no advance symptoms whatsoever.
I heard of people wiring a backup module to a toggle switch to avoid becoming stranded.
@@catsaregovernmentspies my k1500 seamed to always fail in the driveway sofar🙏🤞 after starting up and putting in gear aka stuck at the house 🏡 and easy fix vs no mans land. and yes keeping cold 50-65 f and using better tremale pastry lol from the computer 🖥geeks does help as does keeping the turning + battery/alt 👌ect.
@Logan Forney race cars do it every time. And yes, my truck has one thermo pasted to bare metal on the firewall, wired on a switch. My tach fails, I switch and Ignition!!!!!!!!! I like to street race to the speed limit in my old jalopy and patina'd 79 chevy 3/4 all-time AWD that looks like a slow one. It's overbored, sbc 400, with AFR 227, drag race cylinder heads with offset lifters prove otherwise. People will pass me at full speed when I shut down at the speed limit. I've got them until I do. I had a Honda passport really upset in a 60 zone. I left him at the light, he floored it and caught up to me at 40 mph. I floor it to 60, completely dusting him for a few seconds when I shut down and he goes peeling by me with bald tires to be pulled over with his speed being over 80 mph I'm sure! Lol Baiter!!!!! People hate that old chevy being fast at all.
@@shedred1967 as a teen-26 id have tried street racing but my old man would have strung me up by the rafters lol 😂and then i got married and the wife didn't want to be a widow and or stupid in my 68 C10 or k1500 and more so in the 1967-70 charger ( as one point we "shared that car" and mom hates that car 😂😁 i told her at 14 i was going to buy one so good luck stopping me ( By 21 i had it ) besides most of my bs was in a v6 sedan or the rusty C10 SBC-sm465 4:10fg lol 😂as the bbm charger is a 🚓magnet lol ) or her caddy pissed 😤😡 off so i limted my self to "testing parts " 😉😁 and or not breaking and laws or getting chout
@@shedred1967 is yours a stick? because at 16 my k1500 700r4 went bad and a buddy at the time was parting out is k1500 1-ton sm465 so my mom threw a fit somehow in her mind that = a 6c chevy on full kill lol 😂no way and she would have hate yours as "its a race car" nope lol
I'm bloody addicted to this series!
Thanks Adam, much appreciated.
The problem with electronic ignitions, beyond the thermal/weather related issues, is that their life cycle curve is basically a cliff. Unlike points and condenser systems, they don't gradually degrade with perceptible differences in performance. They're simply on/off and as Mr. Murphy states, they fail at the worst possible time.
Awesome analogy .
Wow, completely corrwct!
I've replaced at least a half dozen in the same vehicle over the years. The most recent was just last week and I got a SLIGHT warning. (not a great warning cuz I didn't realize what it was warning me of) Shut it down hot. Went to buy milk. Came back and it stuttered on startup like it was somewhat flooded. ( it NEVER does that). Drove it home and parked it no issues. Wouldn't go again. Installed spare I bought only 2 months previous. Didn't even trouble shoot it. Just prayed it wasn't a dud right out of the box like the LAST one I got at NAPA!
I've had 2 trucks with the GM HEI ignition module. A 1989 Chevy C1500 and a 1992 GMC Sierra both had the 350 (5.7L). I owned both of them since new and put over 260K miles on each one. I only had to replace the module once on each of them. Luckily, I was never stranded. My friend had a 1990 Chevy C1500 and replaced the module a few times before reaching 200K miles. It turns out he wasn't using "heat sink grease" between the module and the distributor because it didn't come with the module when he bought it. The ones I bought at Autozone didn't come with heat sink grease either but adding the heat sink grease was one of the steps in the replacement procedure in my Haynes' manual, so I bought some and put it on. I like to think the grease helped, but one thing for sure: I was lucky to get so many miles from these aftermarket modules.
As a 70's and 80's era GM tech, seems I remember replacing more failed pick up coils than modules. This issue went away when they eliminated the vacuum advance which would flex the wires on the pick up coil to the point of breaking. I still have a collection of GM pick up coil magnets on my tool box...
yes same here, you can only flex a wire so many times it is going to break
I've been driving GM HEI since 1976 (including in my 77 GMC Motrohome which you have referenced)and never had a module failure. You have to keep all the secondary components in good shape-- cap rotor wires and plugs and gapped correctly (.038") Any degredation in the secondary allows the coli voltage rise to increase very high before discharging. This proportionally (it's a simple windings count ratio) raises the back EMF to the module when it opens the primary circuit. They can take this for a while but not forever. Also the heat sink compund dries and shrinks after 30 years and does not provide good heat transfer. Furthermore some incorrectly use dielectric grease instead of white heatsink compound, which works but not as well..
One thing i notice when i did use dielectric grease After a year i would go back to look under ignition module,and the grease was still there.That clear grease that came with the module would almost or be gone under the module. Now i use the white heatsink grease .When i look under the module after a year it is still plentifully there.eleminating any chance of the module frying.Now to eliminate heat from the coil in cap by getting one to put on the fire wall.
Interesting to keep a spare HEI module in the glove box... kind of like 1960s-1980s Mopar owners keeping a ballast resistor in the glove box! Never really had too many problems with the HEI, but the GM "Optispark" ignition system used on the 1990s LT1 V8s was not known to be one of the most reliable, and certainly not easy to access / repair, being behind, under the water pump. As a 1996 Buick Roadmaster Estate owner with the LT1, I can attest to this.
Exactly Lake.
95 Impala SS owner here agrees putting the water pump over the top of the distributor so coolant can leak on the ignition ,bad idea.
I used to carry around a spare Ford TFI module with me.
Try an optispark in a 92 corvette. One stroke thru a rain puddle and the car starts missing, or dies all together.
New to your channel by the way and enjoying. I did 17 years as a GM dealership mechanic and the biggest component failure that I remember was when they went to the plastic intake manifold gaskets on V6 engines that carried coolant through the intake. The 3.1 or 3100 they may have called it and the 4.3 come to mind. This was in the 90's and Dexcool had come out too. These were 100% failure rate for coolant leaks. Coolant would leak externally and internally at the corners of the intake. It wasn't if but when. You would pull off the intake and those plastic gaskets were in pieces. I think the idea itself was as bad as the component. Felpro came out with rubber coated aluminum gaskets that were much more durable. We were paid a flat rate per job and I did so many I was making triple time on the 3100s. You could leave the rear valve cover on then use a line wrench on the rocker arms to open the valve enough to slide out the push rods and change the gaskets
My dad's last pickup was an 86 Chevy half ton, 4.3 L Vortec V6. His Chevy ate those HEI modules like candy. The V8 version was about 20 bucks at NAPA, the V6 was $100. I was working for a division of Echlin at the time and he asked if I could get some modules with an employee discount. I found out I could buy them for about 5 bucks each, so I got 3 for him. He replaced only one and that lasted for the rest of his life. When mom sold his pickup after he passed away in 1993, the other two HEI modules were in the glove box.
The rest of the known automotive world installs an HEI and makes an oil pump primer out of the old points distributor.
So I have five cars between 1965-1973. The 73 being a Dodge and the others all Ford products. All the Fords use the Pertronix II since it first came out powered through a relay. One car had a first year Pertronix I and all have performed great. However, for some reason the Dodge had trouble with the Mopar system and also blew two Pertronix II modules. I made my own HEI system for the Dodge using an NOS GM Module, a Ford e-coil, and powered through a relay. The module attaches under the Mopar distributor using the heat transfer paste. I get 13 volts to the ignition, great looking plugs, quick start, and so far am now 6 years into.
Yeah I have an HEI on my 340, runs great. Hot spark, and has zero problems with a 10.9:1 compression ratio, or 7000 rpm. I think these systems get a very bad name from GM rushing them into production too early.
Owned several GM's with HEI and only had one module go bad on me. The flaw is when the silicone dries up and the chip frys. Not a bad design when serviced right during a replacement.
I replaced replaced the ignition module on my 1985 Chevy LT-9 engine and it was original. The original mind you from 1985 still functioning in 2023. The problem was a burned rotor probably secondary to old spark plug wires. I went ahead and replaced the ignition module as well and bought a backup to keep in my glove box.
I have only once had a bad experience with Mopar Electronic Ignition System in 1972 to 1989 Rear Wheel Drive cars. It was a 1976 Dodge Aspen SE Station Wagon. Water got in and fried it. Good thing it was still under warranty at the time. The K-Car Ignition System fail point is the Electro- Magnetic Pick-up, the little wires break over time. Should change it about the same time as the Timing Belt on the 2.2 and 2.5 liter engine.
Remember these issues all so well! At our shop we also would see the Ford TFI modules and the 86-92 various GM vehicles with what insiders called "Phantom Stall". On those GM cars we would have to look at the date codes on numerous sensors (crank, cam, MAP/MAF) and replace the ones in question. The worst issue was the intermittent "stall and cranks but won't restart". By the time the car was towed to our shop the car would start right up and could be driven off the tow truck and we were "unable to duplicate the condition". Customers were pissed to say the least. My brother and I wound up doing a series in Motor Age Magazine on how we finally repaired these intermittent problematic cars. Needless to say it took a lot of hours of driving these cars with scan tools and lab scopes connected to various components trying to duplicate the stall condition and catch which electronic sensor was out of range.
One of those cost me a race at Mosport back in 1990. Was leading when it stopped dead.
These porch chats are great! I hope that you have time to continue with them!
A very good series. Always fun to watch.
Maybe because I was in Arizona and drove lots of miles I removed the Points/Condenser and installed the Pertronix electronic kit. I kept the Points/Condenser in the glove box but never had the any trouble. I finally installed a HEI from a used farm truck never had any trouble with it either. I believe everything you say because I know others had trouble so I maybe I was lucky for once.
This man explains it so well I try and tell people about new electronic modules
Ford also had problems with a TFI ignition module mounted on the outside of the distributor, my 1984 Tempo had a recall, and a day before the scheduled repair mine quit and had to be towed.
my 2003 Buick lesabre ICM failed in Chihuahua, Mexico. Due to the scarce availability of parts, my mechanic here in Mexico found a used ICM at the junk yard. I will replace it when arrive in Tucson, with a new OEM. Wish me luck!
I had four Hei modules fail in a month. All standard motor products modules, bought at the local parts shack. I got a Davis module off summit, no problems since.
My '88 XJS V12 HE has a GM HEI module located inside the AMP which is mounted on the driver's side intake manifold. That HEI module is, by far, the biggest problem I have w/the car. I always keep an extra AMP and an extra HEI module (along w/tools) in my trunk. I have had modules last for as long as 2 years, while the last two I had both lasted less than 2 hrs. Prices have doubled in the last couple years (although still around $50), but it's really the issue of just shutting down somewhere out on the road that sucks....sure wish I could find an alternative.
We always carried extra modules in our trucks in the early 80's. They seem to go bad when you hit the gas at the green light. Or pulling into traffic.
I worked for Autozone for almost twenty Years, this part was a Hugh seller and I have tested hundreds of these, the aftermarket does have some problems for quaulity....
Just had to replace ignition modual in a 3 week old Accel HEI. Car died while driving 3 days ago and just fixed it now Was driving me nuts because no one has a video on how to trouble shoot modual. Tested everthing else and all good. Watched 2 vids on bad modual so I said screw it spent another $50 bucks on Petronix Flame unit and started right up. Thanks.
Little known fact. Later air-cooled Porsche and triumph (Lucas electronic ignition) used this module but in a firewall mounted box. If you need the Lucas part, it'll cost you $150 the Porsche part $400+ or you can remove the rear cover and just replace the module in the case for $30.
I had a 1994 Chevy truck with the 4.3 V6 that had that system and after replacing the distributor cap a d rotor my truck would not start. I replaced the ignition module it ran fine. I surmised replacing the rotor which was stuck in place so I had to bang and ultimately break the plastic rotor it made the ignition module fail. The new module had grease you had to put under it or it would cause the new module to overheat and fail.
Another homerun video! When I bought my very low mileage '76 Coupe DeVille back in 2002, I read about some of the horror stories of this module. Even though the car ran great, I went ahead and changed out the module with a new one as insurance. I think it was an aftermarket brand though. Regardless, the car is still running great today.
I really enjoy your videos and always look forward to the next one!
You had to remember to use the insulating paste that came with the HEI module. If that was used, the module was good for a long time.
It's actually not for insulation, it's to help the heat transfer from the HEI module into the metal of the distributor.
@@TheLionAndTheLamb777 Exactly! Couldn't have said it better. Take care. Cheers
The only problem with many of the replacement parts was the source was quite important; as the commentator mentioned.
I would suspect that many failures were due to improper paste installation as well. And, I'm sure build quality degraded over the years as this system was changed and quality was forgotten about.
Hello Adam, nice explanation. In my former spare parts selling job back in the 80's and mid 90`s, the electronic ingnitions systems were a tricky stuff for all old school mechanics who believed that contact points were the real deal. No way, the electronic ignition was something positive devices for the automotive industry, thanks to Mopar, the very first one to featured such an element. The heat inside the distributor probably caused over heating component isolating the power supply, so fot my personal experience, the Mopar system was superior over the GM H.E.I one as I could see over the years, because the Ignition External Module from Mopar did not suffer for heat or humidity, because was an external fitting unit, almost placed above the inner fender dust skirt or over the fire wall. In my Chevy Celebrity I owned some years ago, and with almost over 162.000 miles. that module was the original Delco Remy factory unit!!, believe me, but was little different, with 4 or 5 contact tips rather than your 4 contact module, 1875990 GM catalog part number. They were cheaper to buy, in many brands, such as Wells, Standard, Valley Forge, General, United among many others as well, keeping a higher price for the Delco Remy unit. But to be fair and serious, the HEI ignition GM system is a world class design, very dependable, long lasting performance. Thanks for the info, very ilustrative. Salute, from Bogota, Colombia. Take care, man.
the old mopar system was very good also.nowdays though,its hard to find a good replacement ignition module as they are all chinese junk.
Mopars of the '60s and '70s used a 'power' resistor in series with primary coil circuit to drop the input voltage to 6V after startin g the engine. What happens is: that HOT resistor gets hit with rain water, causing the part to crack resulting in engine shutdown! The engine will start normally, but will shut off as soon as you release the ignition switch!
My 76 Nova went out in the mid 80's but I was lucky enough that it only failed when it was cold, once I took it off and warmed it up with a hair dryer and reinstall it the thing would work fine until the car again sat for 8 hours or so. It took me a few days to secure a new one so I got pretty good at pulling things apart.
Putting some good quality thermal grease between the module and its base helps tremendously.
I have converted two Corvettes, a 350 ci and 454 ci over to HEI ignition during engine replacements, one in a 1965 Corvette and one in a 1968 Corvette. Both have been working fine for over 35 years. Had to replace several caps and rotors, but I have never yet had to replace a coil or ignition module. Don't know why you are having all these problems, but I have not.
The competing Ford Duraspark system had issues too, they used a single low gain transistor, which required high current in the driver circuits with big hot ceramic resistors, which generated heat and the thermal cycles would degrade the circuit board connections. some of the better aftermarket modules (Wells) had a Darlington transistor for more gain and had driver circuits that didn’t produce so much heat.
I have a 65 El Camino,350,th350. My issue is :
I could be driving,or at an idle at a light,and it will die, loose all electrical power,I turn ignition switch off,put it neutral,turn the key,and starts right up...any clue why this is ?
Help
Thx....Amy
The HEI module on my 75 Firebird failed 3 times - strikeout! Replaced the distributor with a points type - no problems since...
Hello Adam. Your channel has quickly become “must see TV” for me. Thanks! 👍👍👍
It typically last around 20 years before corrosion takes it out. The failed modules usually have green electrical corrosion inside on the contacts where they connect to the circuit board. It's actually a well made well insulated part as the module circuit board is covered in heavy silicone epoxy so it resist moisture and corrosion for possibly decades. Usually when they give out, the car will restart in a few hours then conk back out again when the module overheats. I've only had one fail on me but the car was 22 years old at the time and had 145,000mi on it. Possible symptom of it going bad are low struggling acceleration in hot or damp weather.
I had one problem with that module. It was in a late 1970s Chevy 305. I replaced it and it ran to being disposed of because the rings were shot. The HEI ignition was wonderful. I never understood why the spec was 35 thou for the plugs. I increased it to 55 thou and that increased the power dramatically. An old mechanic suggested 55 thou. All of my other cars and friends cars I did that to and everyone was happy about it. That car went from 15 MPG to 18 consistently.
Points - love them while you have them. Friends that I know that still use points tell me that the quality of them are going to crap. One guy does racing in a Porsche. He had to break down and switch to electronic because he couldn't buy points that would work anymore. They're dying out. The only place that I know still uses them are prop aircraft. They have self contained magnetos. Two of them. Some old tractors have Bendix mags as well.
I always carried a spare module in my Camaro when I had it. Mine failed once but it took less than 2 minutes to swap out.
Ford 7.3 power stroke Crank Position Sensor. Most of us owners keep a spare in the glove box and a ratchet,. The gray one now to my knowledge is the last revision. Oh and the fuel bowl heater. I think it’s fuse #12, also causes a no start condition. Pretty common.
My mother's 1978 Chev Monza with the Iron Duke 4. Went through several of these, left her stranded a few times. Knew to let it cool and then would work. Warranty replaced about 3-4 of these. This was the 1/2 moon 4 connector type, I replaced most of them myself. Used the gel as directed. Finally after these 3-4 replacements got one that worked for more than a few weeks.
Adam: Always appreciate your point of view and understand that you are not a big fan of the early attempts at electronic ignition and fuel systems. GM's HEI, variable venturi carburetors, electronic Rochester carbs, and arguably the worst of all... Chrysler's Lean-burn! They were all plagued with teething problems, and the parts available now are ancient IF you can find them. However... you have what 30 or 40 cars? None are driven more than a few miles per year. Rebuild a carb and distributor and the car will stay in tune for a decade if you treat it to a trickle charger and some Sta-bil. Personally, I like modern systems MUCH better. Nine years, zero fuel or ignition system maintenance, original plugs, one new battery. Starts every time and runs like new!
I still like the older stuff. I can replace the engine in my 66 Chevy four times in the same span it takes to replace the head gasket on a PT Cruiser.
I purchased a brand new in 1987 a C-10 short bed pickup with a V6 4 speed that I loved until I broke down because of this module. The second time it broke down I had the module changed again and traded the truck in for a ‘90 3/4 ton Scottsdale with a 350. I wish I kept the truck looking back now.
I have a 1979 C-50 with the small block and an MSD HEI billet distributor on it, and it’s being doing dumptruck work for close to 2000 engine hours now on the same entire distributor.
The voltage regulators late 70s Fords used were definitely wear items. I recall always keeping a spare.
I hate to admit you're right about points, but my 89 Accord has been dead in my yard for the last few years because I can't find a working ICM or pickup coil for it.
I remember back in the '90s paying a Chevy dealer for a new HEI module, thinking it would be better quality than aftermarket. Maybe it was. Imagine my 'surprise' when I opened the Delco box to find 'Hong Kong' on the bottom of the new module!
Even worse were those GM HEI distributors with vacuum-advance. A wire to the captive pickup-coil would break. Then you would need to pull the distributor, drive the pin from the gear, drive off the gear, drive the shaft from the housing, etc....
Worst of the worst was the HEI on a Chevette with AC. It used the same massive HEI ignition-coil-in-cap unit as a V8, but with only 4 plug-wires. You couldn't do anything without first pulling the AC compressor AND its' bracket. Then, if you needed to remove the distributor, the fuel-pump ran off a cam on the distributor-shaft, so the pump had to come out too!
They were originally made in Singapore
Good Video. Had a 81 Chevy Citation Duke engine that modules fail in hot AND cold weather…32 degrees. Also distributer gear that year changed to plastic/nylon. Only car that stranded me 3 times, and I tried to maintain it like an airplane.
I had the same problem. What I learned is not to use the clear gel it is water based and will evaporate and dry sooner and module will over heat not start when engine is hot on hot summer days. Engine cools off and will start. Use the white paste with silver in it for all computers if you can find it.
The distributor on my 1975 chevrolet truck finally failed last July. Don't know exactly what failed, but it was burning hot. I was amazed that an original component (excluding the rotor, wires, distributor cap) could last that long. An original GM replacement cost less than $100.00.
All experience is personal. I doubt you have owned a vehicle with Lucas points based ignition, but these were awful whereas in the last 40 years I have owned 13 cars, bikes and trucks with electronic ignition without ignition problems. My last experience with points was on a group climbing trip to Mexico where a VW camper would not start. The owner was perplexed because he had just laid out a lot of cash on an extensive service. I fished out a plug and found no spark. Opening the distributor and removing the rotor, the points were shut because of a loose locking screw. Using a thumb nail in lieu of a feeler gauge, I reset them and it fired up.
An even bigger headache although not as frequent was the pole piece wires breaking off which then required the removal and complete disassembly of the distributor. yuk. Frankly, while I did always keep a spare I didn't have many of the modules fail.
You're the first person I ever ran across that said the GM HEI modules aren't very reliable, but I guess it's good to listen to all viewpoints. I would buy a replacement module from Pertronix or Performance Distributors.
They’re reliable until they give out.
My mom's 88 Chevy Celebrity died on me without warning. I was young and knew nothing about cars. Luckily my friend's dad knew what it was and showed me how to change it. After that I started learning as much as possible about cars. Now I fix everything myself. So thanks GM. If not for being stranded by a bad component placement, I might not have been interested enough to learn about cars. Now I work at a collision repair/body shop.
I worked in GM garages from 79 -88. The early HEI modules had issues but from like 78 on they were quite dependable. The biggest culprit I found were aftermarket rotors not working. You needed to use a white GM rotor. Black or blue ones would fail right out of the box. You need to do a video on Chrysler ballast resistors. Talk about leaving people stranded!
It sure is critical! So are lots of components, fuel pumps come to mind as an example. These modules indeed had there issues but so did the pick up coil, I’d say this is a larger problem and indeed I replaced more of them than modules. Your point that you need tools to change the module being a problem is true but the pickup coil requires removal of the distributor completely to replace. So yes this part can fail more than other makes and types but I’ve put lots of those on the fender ford modules. I would think statistically the failure rate would be very low compared to units installed and total mileage. Unfortunately you seem to be the statistic, lol.
Poor product and the lack of paste contribute to the bad rep.
Great info as always!
Ps. I also have run a “unitized” gm on my 455 Pontiac which is the only engine I believe it was available on. 72-74. Sort of a test bed for the hei.
Daddy to it I guess with the transistorized being grandpa.
Anyway it is original untouched other than the secondary harness and is north of 160000 miles.
Worst part ever?? Idk but that sudden wtf when it dies on you,, sure makes you think so.
Jim.
The Olds V8's I'd say '75-'77 had .080" spark plug gaps to fire lean idle mixture. This lead to the "rotor" burning a hole to centrifugal advance. Also the plug wire terminal closest to a coil mounting screw would burn through the plastic causing a dead miss on that cylinder. Another issue was rust would lock up the centrifugal advance. That lead to removing distributor taking it all apart glass beading the advance and greasing the reluctor on the shaft. Also the nylon bushings on the weights would fall apart. Thexton at that era had a kit to install new improved bushings on the weights. There's no telling how many HEI's I rebuilt in that time. Oh I might add on the Olds. We'd knock the plugs out of the carb to richen idle mixture and install .035" gap spark plugs.Happy customer. In addition while the distributor was apart a new GM pick-coil was installed. The white and green leads would break caused by action of vacuum advance.
Thanks for the informational video. I couldn't start my car yesterday, but it fires up and is running today. Is there a test for the module or do I just replace and be done with it?
Wonder if a thermal pad on bottom mixed with some very well made thermal paste for added overkill could help the issue a little more.
I built a very good HEI system for my 65 Galaxie 394 .20 over FE. I got a TFI heat sink and attached the4 pin module and mounted it on the fender well. I got the one my circle track buddy’s use with the gel. I have used this on 4 different vehicles. If someone is stuck and I just pull it off and help them get it home, put it right back on with my own looms that hook right to the factory distributor. I also have a 1996 F150 remote mounted coil mounted on the power steering bracket, in common is they have great air circulation and run cool. The secret is a well grounded heat sink, a weather packed loom and air circulation. They live forever. If you do have to get a module, go to O’Riellys and get one for a Cadillac 500, or a 454 heavy duty truck. I have pile of good ones I got at the junkyard all bagged and tagged in my closet in the house for temp and moisture control. I have not had a blown anything running 30 amp relays to all loaded circuits. My ignition is a nice hot 52,000 v and runs at alternator regulator voltage which is 12.7 volts. I plan to add an 870 DP with annular primary boosters and a VS7875 turbocharger with a blow though boost referenced fuel system and hat and a referenced dial a jet on the secondaries. 61, retired but hoping for 750 hp at the rear tires .
A nice talk about electrical components on a cars , GM. I had an 87 Dodge D150 pickup with an 318 V8. I always keep Ed a spare ballast resister and voltage regulator in the glove box. I had to replace the regulator twice and the ballast resister once.
The other gizmo I remember lol
This takes me back to my first car, 1976 Chevrolet Malibu Classic, that module went out at 60000 miles at a gas station.
A buddy of mine was giving me and a complete motor a ride to have it installed in my car. 20 miles from destination the HEI ignition module died , fortunately we had a spare in the back of his truck . Now I always carry a spare in the glovebox.
I retired as a auto mechanic about 15 years ago. In my bottom drawer are a box of Chrysler Ballast resisters, GM HEI modules and Ford Thick Film Modules.
The GM HEI units were substantially more reliable than the Ford units of the same era. I went so far as to mount a second module on the fender well of my 79 Ford truck just in case the operating unit failed. This eliminated the need to rifle around in my tool box looking for a new one on the side of the road. I would simply plug it in to the new unit. 3 times in 3 years.
I never had a factory GM module fail. As a rule I replace the module along with the cap and rotor at tune up time. Easy to change and not expensive to purchase. The aftermarket modules are junk, especially Petronics.
Yeah those Ford modules were crap but i bought the house brands from the auto parts stores. The oem fords were better built.
You can refit a GM module to a ford.
It's kind of neat with a Ford ignition modules when they overheated, you could pour cool water on it and wait a few minutes and it will start right back up generally. Granted, you'll have to stop again when it overheats again before you replace it. But you certainly couldn't do that with the HEI in general motors. I guess I got lucky I never had a problem with any of mine. But I certainly see his point
I had an 84 Pontiac Grand Prix that never had any ignition issues and I owned that car about 15 years. I think it was the early years of these systems from 1975-1980 that had the most trouble.
Yeah I had a 1978 TransAm and I put over 150k miles on it. Only thing the "pick up coil" failed at about 30k. Otherwise no problem at all.
Adam, appreciate the good content once again. You’ve mentioned more than once that you’ve found aftermarket parts to be inferior to OE. I’d like to address that. Disclaimer, my career was almost entirely in the parts aftermarket.
Surprisingly, I’m going to conditionally agree with you. When I started in the aftermarket in the late ‘70’s/early 80’s, aftermarket parts were quite often superior to OE parts. The aftermarket had the advantage of “reverse engineering” OE parts, particularly failed OE parts, and gaining understanding of what caused the failures, and create more robust replacement parts that solve problems.
However, the technological revolution that occurred throughout the 1980’s and 1990’s made many parts much more expensive, and diagnostics much more difficult thus costly. Consumers began to push back on the cost of automotive service, service providers pushed back on parts suppliers, who pushed back on manufacturers. To cut costs, manufacturers would cut expenses in manufacturing or source parts from low cost providers.
There are still brands in the aftermarket that don’t succumb to this pressure and offer high quality parts, even parts that fix OE problems. A good rule of thumb is the old adage, “you get what you pay for”. There’s a chance that a low cost part, when price is compared to an OE brand or known high quality aftermarket part, may have some deficiencies in quality that will disappoint in performance or durability. While this may not ALWAYS be true, proceed with caution on low cost parts.
Thx! I was also in the auto parts space for part of my career.
@@RareClassicCars with a manufacturer?
So if you've got a car with an aging HEI distributor, what do you suggest to get it good as new, rebuild or are there good quality replacements available?
My first ever vehicle was a 1994 lowered C1500 (Still have it) and the Accel Ignition module behind the cap decided to have a stroke while I was driving and it instantly shut off. Back then, I wasn't as knowledgeable as I am now about C/K series trucks so, I literally had a panic attack on the side of the road. Lol, my father is an expert mechanic and helped me fix it.
I also worked at a Napa store for 10 years. Think I sold 1 HEI module. Sold dozens of Ford Modules Part # TP32. Also had a Chevy wagon in the shop once that had most of the distributor cap missing and it still ran!
Good advice Adam on the HEI. My Chevelle had an old MSD electronic ignition and I debated putting an HEI in it instead since the MSD was failing intermittently, yes leaving me stranded a few times! It was tough to troubleshoot since MSD kept saying their ignitions don’t fail intermittently. Not true! Long story, I ended up getting a new MSD, so far after one year no issues.
I just replaced the ICM in my 1977 monte carlo this past weekend. It died while pulling out of my driveway. Remarkably it was the original GM module.
Hi, great story.
I am based in Australia and our local GM's are called GMH.
We had point is GMH until 1982 ( strange as local chryslers got them 1973 and ford 1978/1979 )
We used the same bosch 4 pin model you should, however as ours was basically same 6cly from 1964 and same V8's from 1967 we also used the same distributor and what the factory done was added a metal "shield / plate" on the lower distributor body and mount the hei module on that metal plate
A short 4 pin wiring harness went into the lower distributor metal body - while the distributor was basically the same and electronic internals instead of points they did get a larger diameter cap and rotor to stop the arcing between each lead terminal in the underside of the distributor cap
Now these ran great for 5 to 10 years then the problems emerged, originally with V8's as the lower distributor housing is shorter and mounted basically rear engine like a gen 1 chev 350 / mopar small block
Plus the module was in the rear so it was a pain, to note the rotor position, remove the distributor and work on the plate, new module would work 6 to 12 months then the same problem - the importance of the thermal paste was basically unknown and many people did not clean the surface and re apply the thermal paste
6 cylinders were actually OK as they were on less vibration engine, not driven as hard and the module faced east west with plenty of clear fresh air and not much water - there problem was being parked outside and the metal plate would tarnish and thus bad conductivity between module and plate
A trick everyone had was throw a bottle of water over the module if it starts it was hot and you can run the car for another 30 mins / few days - if it did not start it and it was a hot day it was probably fuel vapour lock - another problem as we did not have fuel pump return lines on mechanical fuel pumps
I had a issue with my car, the sparky was busy and he said " can you fix it yourself" i say NO, he said can you use hand tools, i said YES - so he spent 1 minute telling me what to do, i removed the dizzy, took of the module, took of the wiring harness, used a hand file and sandpaper on the mounting plate, applied the paste and bolted on a new module - reinstall the dizzy and he got me to look where the dizzy was now and rewired the firing order from there - turn the key - bang it fires up
He just charged me the counter price for the module - and said if i have a problem come back, if the car runs hot ( as it was a V8 and the commodore has a cramped engine bay ) i can come back and he will do a mod, i told him i would see him next week and the car had messy under dash wiring due to a prior owner being a butcher and a radio install, he said if i promise to come back he would order the nder dash harness from GMH and help me out
I week later i turned up he had the harness and i was simple to removed from the fuse box power and use the new speaker wiring, he asked about the HEI and i said fine, and he said we will do the mod - it was simple, it was a simple rectangle hollow box section of aluminum - he had a few 6 foot lengths of it, he chopped of about 4 inches of it, ran a large screw into the firewall and mounted the alloy then grabed a premade 4 pin extension harness he had and with new thermal paste moved the bole from the dizzy to the firewall, the hollow box section had better thermal conductivity plus being hollow and on the firewall was no more vibration of the engine.
That worked for the 8 to 10 years i kept the car, he also had some mopars and used that module instead of the factory ECU
The secret was simple use genuine bosch component, keep them as cool and vibration free as possible
I had a couple go bad on me, and yes, the original GM component is a much more solid state. I always keep a dual point distributor in the back seat just in case. The points never wear out when the dwell is set perfect, and GM makes it easy to set while running. Also, never buy a Mallory brand HEI. Their reluctor is thin and fragile. I've had two fails, both in winter. Never again. My Mallory points and their unilite strobe have never failed me, ever. I won't touch their HEI until that reluctor is addressed. Accel, MSD, or Progression Ignition all day, every day when it comes to HEI. My stock replacement Accel distributor even makes more power than my old Mallory performance HEI on the dyno. I was surprised again, though the module went out three months later.
I have never had a GM HEI module fail in any of the dozen or so GM vehicles we have owned that used them. However, I always placed generous amounts of electronic-grade heat sink grease between them and the distributor bodies as soon as I could after purchasing the vehicles because I was aware that they ran hot. On the flip side, I ended up donating a Ford truck that ate firewall-mounted ignition modules on a regular basis because I became so sick and tired of dealing with them. And I had an MSD 6A module on my last truck (K1500 Chevy) that stranded me on several occasions. I would be driving along happily and then sudden silence with no restart and absolutely no prior warning. It got so bad that I carried a spare MSD box (despite the cost $$$) before I gave up using them completely..!
Had one fail on my 1991 Chevrolet Silverado. Turned into a real mystery finding the problem. Turned out to be the dielectric grease, or heatsink compound had degraded in turn overheating the module, the grease was there to prevent overheating the module, when the module was cool the truck ran fine. As soon as the module overheated the truck would stall and refuse to start until the module cooled back down.. I replaced the module and installed better module grease, heatsink grease and never experience the problem again..
Hey!! I have really been enjoying your channel. I just wanted to comment I have run quite a few vehicles with HEI and never had the module fail (including my 84 K10 which I've owned for 22 years). Maybe I'm just lucky. But I have had to replace the module in my 93 S10 Blazer four times in the past 11 years. I agree that new parts store electronics aren't as good as NOS. And I owned an older air-cooled Volkswagen that was notorious for eating points. Keep up the great work and thank you.
I had a 82 olds cutlass supreme with that module it was a V6 I had it replaced at least 3 or 4 times it didn't seem to make any difference if they used the jell or not
i have never had any issues with points either. had a bad condenser once. even the dual points in my 1967 300sel are super reliable.
Thanks for the info. I am working on a GM HEI, and at this point, I have had a great deal of trouble with timing the car. The timing mark is basically, all over the place with a variation of about 10 degrees. How should I fix it, I wonder? I'll work on that and possibly send some information which I've learned to you. Wish me luck!
I agree with keeping original points ignition in a car. I have 4 of them, they all run great. You just have to understand them and keep them in tune. Won't leave you stranded if you do that. I'm a career mechanic with my own shop but I started as a mechanic in a GM dealership in 1991. We were never short of work let's put it that way. The early port injected engines had poor driveability. GM actually had a "tap test" where you tapped on the Mass airflow sensor or the ECM with the handle of a screwdriver with engine running. If it stalled the component was bad. The problems were from stem to stern with quad 4 head gaskets, 440 transmissions, nylon timing gears, engine leaks, steering racks would lose assist, driveability issues. They put a longer dipstick in the 2.5 to reduce oil capacity to 3 quarts. Then they would run out of oil and throw a rod through the block. Those had loud timing gears too. We figured out how to change those in the car. You were supposed to pull the engine and remove the camshaft because it was a press fit gear but we would cut the old gear then tap threads into the end of the cam to press on the new gear. And that's the tip of the iceberg. I actually loved it because you became a great mechanic with so much to figure out and repair.
Interesting on the 2.5! What would you do once you tapped the threads to get the new gear on?
@@RareClassicCars You would run a nut up the bolt first then a big washer. Warm up the center of the gear. Then thread the bolt into the cam and run the nut and washer down the bolt against the gear to press it on.
I couldn't disagree more with your assertion that the GM electronic modules are one of the worst components in the auto industry. Leaving a person stranded was far less likely to happen with an ignition module than the "good ol' points" system. Points systems are in CONSTANT failure mode as the rubbing blocks wear, condensers fail, points arc and corrode, etc. After-market replacements were and are often cheap imitations of the originals, so you can't bash an OEM part for that failure.
I worked as a mechanic at a GM dealership and can't recall ever replacing a failed ignition module. I drove a late 70's Ford and at the very least, had to annually replace the failed 'brain box' mounted on the inner fender. Ford's electronic ignition was much more failure prone than GM's, and let's not even discuss the Mopar junk that was mounted to the air cleaner - that system was NEVER any good.
Age is not an asset to electronics so if you're asserting that the original parts are currently failing on low mileage cars from that era, then that's not even a viable argument. Replacing a GM ignition module is a quick operation, one that takes much less time than replacing and setting points.
A preventative measure is to refresh the compound between the module and the mount, and flat file the mounting faces. The white Goo never provided is "Super Lube #98003 Silicone Heat Sink Compound" (made in USA). The replacements come with dielectric silicone grease that although is not inhibitive to heat transfer, does not enhance heat transfer either. Such usage is to prevent water ingress and corrosion only. Do not use compound meant for computer CPU's because the stuff goes bad sitting for 3 years or while in use for 5 years (such as a great Noctua Brand paste).
The Super lube stuff seems to last a looooong time (decades easy), and is what you find on everything (MOSFETS, etc...) Zinc oxide in the product makes the silicone transfer heat better. Unfortunately I have not found anything with a better heat transfer ability that has the extended service of the plain white Super Lube stuff. On my ford I modified the distributor mounted TFI or TFI-IV (Thick Film Integrated Ignition) module to a later designed fender mounted module. (EEC-IV) I'm working on a video documenting the mod. Ill try and remember add it to the comment when finished.
If you look on my channel, you can see I made an ignition system on my car using COP and it didn't improve reliability. I was surprised at first, basically there are many arguments going for it, and it still might, but long story short, what I learned from it are: 1. New isn't always better (the allowed dwell times were really low, lower than on the single coil on the old system that had to do all the cylinders!) 2. Coils on a heat cycling and vibrating place last shorter. 3. IGBT transistors on heat cycling and vibrating places last even shorter (best have the IGBT pack located somewhere further away from the engine) 4. IGBT driver circuitry inside the COP's is even worse, best halfway solution might be to put just coils in the COP's and let the drive circuitry and IGBT 'amplifier' sit somewhere less shaky and less hot.
I had a 1980 Bonneville Brougham coupe where this issue with the faulty module reared it’s ugly head a few times. I was 17 at the time and had no idea what the issue was. I called my father, told him what was happening. It took him all of 3 seconds to nail down what the problem was. Fond memories now.
Let's do one together on the early GM cable driven window regulators that was my bread and butter throughout the first decade of the 2000s. Grand Am, Alero, Intrigue, LeSabra, and so on.
Or go back further to the plastic tape window regulators. We had tape in bulk rolls and were required to replace the only tape. Ridiculous!! Funny how, now we almost never do electric regulator repairs on the newer stuff. my paycheck is hurting.
@@scrappy7571 yep all those were guaranteed income and now they finally figured out how to make them good.
I’ve never had the problem with a GM car. But I have seen numerous Chrysler products that did. To be fair this was early electronic ignition and they are certainly better. On GM cars I replaced the original equipment with Accel units and never had one fail. Fiat used the same GM module and had few problems possibly because they mounted it on the inner fender.
A few years ago I had a sailboat with a gas engine with points & condenser. It quit a mile or two from the marina. With a following wind of about 12 - 15 knots I had little problem getting there after raising the sails. But being the only responsible adult aboard that knew how to sail and the wind increasing to about 20 knots the problem was how to slow down. Taking my hands off the tiller resulted in a very wild spin but with one hand on the tiller and the other to drop the sails I got it into port after hitting the dock. The boat got away from me while trying to tie up by breaking the lines and I ran and jumped aboard. A power boater towed me in. I vowed right then to NEVER trust points & condenser again.
Well. I can understand that!
If you ever worked on a Ford DuraSpark you will appreciate the GM HEI module. I have owned northward of 30 GM vehicles and never had an HEI module fail. I have upgraded Fords and GM points to HEI and resolved the issues.
Yes, I have had my 1976 ElCamino for 30 years and have had 2 faiures, one where the car would not restart after shut off and recently had a misfire with lack of power and hesitation only under low speed acceleration and suddenly disappeared, I immediately replaced the ignition module and never had any repeat. Also as you say the aftermarket Chinese modules are notoriously unreliable for voltage regulators also. I bought a new rebuilt GM the cheapest one O'Reily's sold and two failed on the second restart, after jumping the regulars I found the regulators defective. I returned the second one and refused a third one of that brand line. I said I need a better quality unit and they said I could buy a better brand, and I said I will not pay the difference. They gave me a lifetime unit at no additional cost.