A TBI distributor for your race car?
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- Опубликовано: 12 май 2024
- Why would you want to put a TBI distributor in your race car? Well, for one thing, it has a smaller diameter cap than an HEI. It's also much less expensive than name-brand ignition systems. It works on the exact same principle as every other distributor too. Most of us toss the module in the trash and use an aftermarket ignition system to fire off the magnet pickup. The TBI distributor is a solid shaft so it is locked and phased right from the factory. They are easy to hook up and very reliable.
EDIT: towards the end of the video I was showing how the module sits in the cap but I had the module backward, oops hahahahaha 
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Thank you, had no idea you could use these with a spark box.
Thanks for sharing Bruce! I’m running an HEI , locked out with just the pickup. It’s wired to a 6AL-2 programmable and stock coil in the cap. I’m gonna hunt one of these TBI units down next time at the junkyard to give me more room :)
Good info!
One recommendation when using one of the TBI distributors, is to check the magnet on the shaft.
It was very common for them to crack and cause poor starting and other driveability issues. Replacing the shaft is very easy and only takes a few minutes.
I've replaced 100's of them over the years!
These distributors are a great option that work as well or better than most aftermarket ones. If you pick up one of these distributors used, make sure the bushings are good and the shaft doesn’t have any play in it. And when hooking it up to an MSD box, be sure to read the pdf/instructions thoroughly. If I remember correctly, depending on which box and pickup you have, it sometimes requires that you reverse the ‘polarity’ of the pickup wires. Always check your phasing. This is a great video.
Yes, checking the phasing is important and easy enough to do but is often overlooked. Thanks for your input.
Old school ingenuity, build/don’t buy! You can build it for street (and /or )all the way to make it jump off the starting line
I always thought they were called Big cap and Small cap HEI distributors. The HEI module and external HEI coil work together, the module provides maximum dwell to saturate the HEI coil for very hot spark. I have a large cap in a flat head Chrysler 6, and a small cap in a Slant 6. Both engines are in forklifts. I got tired of weak spark and rough running in cold/damp weather. They run much better now, been working flawlessly for 20+ years with the parts in them from the junkyard. The HEI is supposed to be good to 8000 RPM, and will throw a spark 5/8" long reliably. Ford and Chrysler adopted the design when their own electronic ignition systems didn't work so good. You can get after market HEI distributors for Fords and Chryslers.
The distributors are always phased properly because the cap contacts line up with the reluctor wheel when wired with the correct polarity.
What about the 4.3 v6 distributor using a 8 point cap?
Good question...I'd check the magnetic pickup and see if it has 6 or 8 points on it. I'd assume it would only have 6 so that won't work. I might need to see if I can find one of those at the wrecking yard next time I'm out there and do some experimenting
6 cylinder distributors won't work in 8 cylinder engines due to v6s having 6 pickup points vs v8s 8 pickup points.
like to know the measurements of that test bench you built. and do you have a degree wheel to mount on it?
For the design of this distributor tester, I searched for "homemade distributor machine" and a very nice write-up came up so I pretty much copied that plus I made a few tweaks to the design to make it my own. You can make it larger or smaller depending on what you plan to do with it. In my case, I wanted to have enough room behind the distributor holder to mount different ignition systems for testing.
Reading the write-up, that guy used a degree wheel to do timing checks. I tried that but the degree wheel was too heavy...instead, I used corrugated plastic because it is light and rigid. If you look through some of my older videos, it shows how this works. I made it so I can run this unit with or without the wheel.
I will warn you though...once you build this, you will spend hours and hours in the garage playing with it and all of your friends will want to bring their distributors and ignitions over for you to test LOL. This has been a lot of fun and I can actually test ignition systems before I mount them in the car which can save time when trying to trouble shoot weird issues.
Which one do you suggest for race cars?
Pretty much any distributor that has a magnetic pickup is going to function about the same. If you plan on running locked-out timing then for simplicity, the TBI distributor would be easier. The HEI can be locked out but it does require a couple extra steps. As far as performance is concerned, again they should all be the same.
@@BruceCoggins .
Thanks for your great information,
What about marine engine?
You will need the marine version which is waterproof. If locked out timing is what you're looking for then this will work just fine.
Is it true, the factory module has a small amount of built in advance? Heard the marine guys use these in boats.
An electronic control module is simply the electronic replacement for points. A module has a certain amount of dwell built into it...as a matter of fact, it has what's called "expanding dwell". Google search HEI expanding dwell and you'll read some interesting information. Now, I believe the 5 pin module has a retard function but not an advance function. They were used in the early computer-controlled distributors back in the mid to late 80s.
@@BruceCoggins I've read about the variable dwell. Mainly used to reduce coil & module temperature at low engine speeds by reducing on time. Then at higher speeds allows for more coil saturation. High tech back in '74 lol. Pretty sure the marine guys say the factory module on TBI modules will slightly advance timing as rpm's increase, it was some sort of default if the ECM failed to control timing. Just wondering if you ever noticed or can confirm.
@@scrappy7571 I have not tested that but I don't really see how the module can change the timing by itself. Let's look at the wires on the module...There are 2 connectors on one end of the module...these go to the coil positive and negative. On the other side there are 4 wires...a ground (black), timing by-pass (tan with a black tracer), purple - this is the reference for the ecm to run the fuel pump after it sees a signal, and a white wire which is for the EST (electronic spark timing) so that would mean the computer can adjust timing. This module does have dwell but that doesn't change the timing. I may be missing something but I still can't see how the module alone will change anything with the timing.
Questions like this get me thinking though...I will try to come up with a way to test that theory with my wheel installed on the machine and we'll see if that holds true or not without the use of an ECM. Thanks for your input...now we have more things to test ;)
@@BruceCoggins Cool! I have been pondering this for years. Hope you can confirm it does or does not.
If you have a gm module try to use it. Aftermarket modules usually have "unnecessary" features removed.