5 Secrets For Tuning And Adjust Holley Carbs That The Pro Builders Wont Tell You | Carb LS |NW Ep.60
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- Опубликовано: 11 фев 2020
- Tuning Holley carbs are probably the most widely used carb is all of automotive history. The Holley 4 barrel is a staple among racers and cruiser a like but too few people really understand what goes on inside their Holley carb and too many decide to ditch the old carb in favor of a new one. I am here to share 5 secrets you can employ TODAY to get that Holley nice and tuned and running better than ever in true DIY fashion. I'm put to work these 5 secretes to get my Carb ls going so these are definitely something you need to keep in mind. Tuning a holley carb is what separates the boys from the racers. Depending on how well this video does, I'll be breaking up and going into full detail of what goes on specifically in the different circuits as well so stay tuned!
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I’ve been working on carbs for years. This was an awesome video. Even I learned something from it! Keep up the great work! I look forward to seeing more!
Thank you sir! Much appreciated!
I had to reduce my idle feed restricors and drill a hole in each of my butterflies to get my transfer slot closed. This made everything else easier to tune and you don't "loose your tune" do to weather/temperature.
My engine isn't radical enough to need it yet. Most modded engines I see just need a 4 corner idle and to crack open the secondaries a bit.
I really like to see the younger guys figuring it out, good video. I've been doing this for 50 years, no A/R gauges or any special tools but 98% of vehicles used carbs in my day, now all I do is fuel injection and LS swaps. We used to read the spark plugs and tailpipe soot and yes, you're correct, we were over carbing then too, most times over camming too. A normal 350 ci. engine consumes 500 cfm of air at 6000 rpm. A 600 cfm 1850 like you're holding will feed a 400 no problem and the driveability will be great. You might give up a few hp on top but 99% of the time you're not there. The power valve is very important and using a vacuum gauge you can find your opening point. Most Holly's ship with a 8.0 because there're usually jetted to rich anyhow so once you lean them out you'll need to go to a higher number to richen the mix a little under acceleration when your vacuum drops. The Carter AFB's (Edelbrock) and Quadrajets are much more forgiving because they reference the vacuum for mixture control and with those tiny primary bores the Qjet is just tops on the street. I ran them on all my cars back in the day and they were very crisp and when those big bores in the back opened up you could flow 750 cfm if needed, the air door is adjustable and you can dial them right in. All in All a pretty good video, keep it up.
Great points, really appreciate it!
I prefere carburettors to, as i reckon' used properly they produce more horsepower. Actually i get better results from a duel-throwt,down-draft carbuettor unless i am using a supercharger in which case i will use a holley style carburettor minus the metering-blocks, enjoy raceing
David Vizard's book on super tuning Holley carbs is a great source
Ive been wanting to buy a holley book but didnt know which to get. Thanks for the recommendation!
NightWrencher The "Holley Carburetor Handbook" by Mike Urich is the go to bible for 4150/4160s, its had many editions but the small red book is packed with the most basic rebuild and tuning information and is easy to understand with good illustrations of all the fuel circuits, functions and relations to each other.
I was able to quiz myself on carb malfunctions by symptoms and sounds after reading this book.
I’ve watched a few videos of Vizards. He must be smart, but the videos I’ve seen of his require me to buy something and as an amuteur it’s not viable
Great video, thanks for breaking things down. Not all who watch your videos know a lot and have to look at videos like yours for advice. Keep up the good work!
Thanks so much man! I really appreciate it!
Didn't anyone teach you to clean up your room? Clean that table up bro.
Great explanation! Thank you!
Youre welcome! I've got more carb videos in the Holley Carb Secrets playlist if you want to learn more!
Good info! Thanks man.
Thank you sir! 👍
Here is a simplified yet, accurate description of the Power Valve, and it's function in a Holley Carburetor from Holley it's self:
"The power enrichment system supplies additional fuel to the
main system during heavy load or full power situations. Holley
carburetors utilize a vacuum operated power enrichment system
and a selection of power valves is available to “time” this sys
tem’s
operation to your specific needs.
Each Holley power valve is stamped with a number to indicate the vacuum opening
point. For example, the number “65” indicates that the power
valve will open when the engine vacuum drops to 6.5" or
below. An accurate vacuum gauge, should be used when determining the correct power
valve to use.
A competition or race engine which has a long
duration high overlap camshaft will have low manifold vacuum
at idle speeds. If the vehicle has a manual transmission, take
the vacuum reading with the engine thoroughly warmed up and
at idle. If the vehicle is equipped with an automatic transmis
sion,
take the vacuum reading with the engine thoroughly
warmed up and idling in gear. In either case, the power valve
selected should be 1/2 the intake manifold vacuum reading
taken.
EXAMPLE:
13” Hg vacuum reading divided by 2 = 6.5
power valve. If your reading divided by 2 lands on an even
number you should select the next lowest power valve.
EXAM
PLE:
8” Hg vacuum reading divided by 2 = 4 power valve.
Since there is no #4 power valve you should use a 3.5.
Most of the popular Holley “Street Legal” and “Street
Performance” carburetors incorporate a power valve blow-out
protection system. A special check valve is located in the throt
tle body expressly for this purpose. This check valve is designed to be normally open but will quickly seat to close off
the internal vacuum passage when a backfire occurs. Once
closed, the check valve interrupts the pressure wave caused by
the backfire, thus protecting the power valve.
If you have a carburetor older than 1992 (or you have experi
enced
an extreme backfire) and expect a blown power valve,
use this simple test.
TEST:
At idle turn your idle mixture screws
(found on the side of the metering block) all the way in. If your
engine dies the power valve is not blown."
Holley also has a similar explanation in their video but its just a rule of thumb. Each engine application is different and should be tailored as such. For example. A 350 in a corvette will require a different powervalve than say a 350 in a 2500 truck even if the rest of the engine is the same so simply going off idle vacuum tells you very little about how early or late you need the PV to come in. Its a much more complicated system than most people think, especially when comparing the relationship of PVCRs to jetting.
@@NightWrencher True, although the different variances are usually related to different cam profiles. If you drive the vehicle at various steady speeds and observe the vacuum readings, you can select the correct power valve which indicate readings of the closest opening point about 2" Hg below the
lowest steady speed engine vacuum observed.
@@Rick-O-Shay60 thats true but you dont see that in the holley explaination.
Great vidio the most I ever learned about holley
Thanks so much!
Nightwrencher just want too say you are very educated at carburetors buddy your advice is the best I’ve heard in a long time
Thank you! I really appreciate it!
I melted one of my boosters on my 1850 main body. Ended up buying a new main body. I need to learn how to swap those out. Thank you for learning me something been dreaming about carbs. And brraaaapppp
Theres a special tool you need and its more expensive than s main body so just be careful next time 👍
@@NightWrencher OH I WILL learned starting fluid means somethings wrong. And dont use that shit
Exactly 👍
Another great video
Thank you! Much appreciated!
Really glad there are young people like you learning this stuff. I've been trying to tell old farts this stuff for years!
They dont know because they dont wanna know 🤣
@@NightWrencher I started out just like you, 30 plus years ago. Now I have a very busy shop and I’m really glad I switched careers. I used to be a radio news reporter, which was fun enough, but this business is much more rewarding in many ways.
Thats awesome man 👍
have a 383 with alloy heads and big cam,670 holley,semi hi rise weiand manifold,what sise main jets would you start with ?
Nice video
Thanks again sir!
I run a Quick Fuel QFX 1050 "Pro-Street" Dominator 2-circuit on the street, and I'll tell you what.... It has been the BEST carburetor I've had in 30 years. The car starts right away after 2 pumps, idles within a minute or two, has the crispest throttle response out of any 4150 Holley I've had, and holds a tune incredibly well. It never loads up and will idle forever. The dyno tuner said the carb was real close out of the box, and just needed minor jetting and air bleed tweaks. Everyone says, "You can't run a Dominator on the street!!" Well, I'll never go back to a 4150 again after experiencing this Dominator.
I hear theyre really good carbs
@@NightWrencher I'd buy another, that's for sure...
You can tune everything about that carb, especially the PV, with a vacuum guage. I absolutely don't understand all of it. I just know they have been tuning carbs for a lot longer than they have even had AF sensors😂 That AF guage will sure make things easy. Nice vid!
The wideband makes tuning faster and more exact. It also lets you identify problems faster too.
@@NightWrencher information is key to success in anything. More of that is always better.
Love it real tech has PB Blaster ready at hand .
Lol thanks
Good vid.
Thank you sir!
@@NightWrencher thanks for the great content❤🇺🇸
Great info man! Got a question.. I have a 70s wood chipper that has a 351w with a externally governed 2 barrel Holley 2300g. It has a lean bog when the clutch is engaged at 1000 rpm. The engine turns this massive flywheel that requires all the power it can get at around 1000rpm..so my question is what power valve I should use... The accel pump is set up right, I was thinking of a 10.5hg or a 2 stage if I can find it....also, since the 10.5 is also hard to find, could I theoretically turn the brass nut inwards on the power valve to reach around 10.5hg? Given that the spring will doesn't plateau before that?
Hey man, sorry for the late reply, I've been thinking about your issue these last few days and Ive got a few suggestions. First, you need to remember that most of our modern fuels are not pure gasoline like the old days and some are actually rated at E10 meaning it has a 10% ethanol rating. The ethanol allows us yo run more timing and higher compression ratios with reduced risk of knock. The downside is that it requires more volume to produce the same burn as older gas. I would break out the vacuum gauge and set the idle to highest vacuum reading, keeping both sides square and lower the RPM back down get it to the right idle. I have a video on that on setting the idle. Once you have that, get it up to the rpm you are having trouble at and check the vacuum reading. Remember that the PV adds fuel to the main circuit only so if the throttle is not open far enough, the higher PV is not going to do anything. I feel that your IFRs are going to be too small and you might be running lean. While youre duplicating the problem, place your hand over the choke tower to see if it clears up or gets worse. Clears up, running lean. Gets worse, running rich. Try all that and get back to me. Good luck!
ruclips.net/video/gW55D00zpvg/видео.html
You might want to go even go a little higher in rating for the PV and look at your plugs, are they white ? Your running to lean, they should be tan so maybe you need to go up a few numbers in size on your main jets and set your mixture with a vacuum gauge looking for the highest reading. Just off idle at 1000 rpm is a tough place to read but from what you describe it's not the accelerator pump shot.
Only issue I keep running into with my truck avenger is it's stupid I mean stupidly rich that if I don't let it sit in high idle for 5+ mins it will end up fouling plugs, and sometimes if it's done it's cold start idled down if I try to give it gas to accelerate quickly it will start to run rough but then clean up after a bit of driving
Yeah, truck avengers are jetted really rich. Thats my only reason for not getting one
I wish you were local haha. I'm new to carbs and bought an old car with a QF 680 and it is rich! I can't figure out what the problem is
I got a tuning video with the "Tuning Triangle" that might help you out!
@@NightWrencher I'll look it up
Will a holley 4412 carb work on a 5.3 vortec? Will it be big enough to run the engine?
Itll run the engine and will have pretty good low end response and torque, even save a little on mpg. You might lose a little power but itll be hardly noticeable
@@NightWrencher thanks you for that info. Very helpful god bless.
@@frankrenteria4370 any time! That's why I'm here
383 stroker, 4150 750. Setting idle air I cant get any higher on afr than 12.8 or so. Well I can but then when I put in geat it wants to die. So back out to 12.8. That seems too rich. Reading it's from too tight of a converter but it's a ptc 2600 stall. What can I change to get closer to 14.7?
Car runs fine at 12.8. Transfer slots are squares.
Cam selection also plays a big role. If its got pleanty of lope, it will fool the AFR gauge into seeing something thats not there. I recommend increase timing at idle if you havn't already and tune by vacuum gauge.
Let me know how it works out
Another tip would be to install a carb with 4 corner idle if you dont already have one. I can usually set a cleaner idle with a 4 corner holley
I had a question about the primaries keeping the square in the transfer slots some say that if you need a little bit more idle speed it's okay to put that Alan hex key in the secondary adjustment screw and lightly crack that open keeping the same transfer slot exposure in the primary in the secondary to have them equally ajusted. I'm wondering about the secondary metering block if you have one which I do what about the IFRS in the secondary should those be drilled out to 35 or so as well as the primarys ? I'm understanding the theory of trying to keep a carburetor square all the way around with the transfer slots I have a 600 CFM vacuum secondary slightly cracking open the secondary butterflies to have an equal balance between the two and not open the primary transfer slots too much but wouldn't you be more rich at idle by cracking up the secondary screw ? . It would draw fuel from the secondary IFR or not ? I have it has a very small adjustment from the idle screw barely touching the adjustment tap from zero to half a turn if I go a little more about an eighth of a turn more it will expose a hole just under the transfer slots im guessing that"s the full manifold vacuum port hole do you adjust your secondary butterflies for a Foursquare transfer slot or you leave your secondary closed ?
I feel like I just answered this same question last week but I'm not sure. Basically, if you have a 2 corner idle carburetor, do not touch the secondary idle speed screw. Since all 4 corners are controlled by the front screws, if you open the rears, it will only act as a vacuum leak so do not touch the rear idle speed screw on a 2 corner idle set up. With that being said, if you have a 4 corner idle carb, the rear IFRs will control both the fuel going into the idle circuit but also the rear transition circuit during half throttle. The IFRs are tuned to the air fuel ratio of the transition circuits and then turned down even further by the idle mixture screws for the idle circuit.
@@NightWrencher You did lol I asked the same question on two different videos why ?🧐 Don't know.
Anyway I finally seen the holes in the IFR you were talking about I needed a super bright led flash too see them they were small undrilled less than 0.33 so I'm thinking 0.28 I drilled them to 0.35 I always had a super Rich smelly idle anything over 12:50 on AFR it would act up and not like it hope the 0.35 helps .
@@TheThirdWheel618how is opening up the IFR gonna help a rich smelly idle?
@@jeremymyers5643 From what there saying it allows more air in that's the ? I ask .The hole is tiny from Holly like 0.28 when I set my idle mixture it wanted a Rich idle in the 12.50 if it went to 13.00 13.25 it would hesitate on take off .
I have a few metering blocks I drill one to 0.35 haven't tried it yet also I bought the pro-form adjustable both need testing .
@@TheThirdWheel618 I reserve the right to be wrong, lol. But I think your confusing idle air bleed , with idle feed restrictor. Air bleed is above booster outside of carb and let's air into the fuel, idle feed restrictor is in the metering block and restricts the total idle fuel in circuit. That's how I understand it anyway.
My 650 keeps running rich at idle smell and black smoke . When I lean it, vac decreases. Any ideas?
What if you try to richen it, what happens?
My other issue is vapor lock in the line even with a fuel return system
Vapor lock is a little tricky to get rid of after you start experiencing it. When I started dealing with it, I installed a 1 inch plastic carb spacer and dropped the fuel level in the bowls a little bit. I later swapped to a 2 inch spacer and don't have any vapor lock issues
You learned all this in a year? Study for 2 and operate on my wife's brain 🤭
Lol, when you daily drive a carbureted engine hundreds of miles a week with a vacuum gauge and AFR gauge hooked up, you tend to notice the patterns and once you apply the changes, you can confirm the results or change your method of attack. It gets a little repetetive but after you get it, you get it.
@@NightWrencher I'm just learning a little bit about my carb, just really started about a month ago, nothing major. Playing around with the simple stuff like choke, idle speed, accelerator pump spring settings. I'll keep up with your videos--- 🤜🤛
That's great man, just take it one step at a time and you'll be a pro in no time 👍
What AFR Gauge do you recommend?
Im running an AEM gauge from summit. It was 180 free shipping and has worked great for over a year now
Thank You for all the GREAT TIPS... On my dual exhaust w/ a cross over where is the ideal place to install the bunge/ probe/ chingadera lol😋?
Within 12 inches from your collector on either side of the exhaust works fine. You dont need to install it where both sides hook up if the crossover is too far away
@@yazming1720 "chingadera" 😂😂
Ive been building hot rods for 20 years. You dont need an AFR gauge. All you need is a Vacuum gauge. Lots of videos from old timers on how to use them properly for tuning. They were the only thing needed for 60 years and racers will only use a Vacuum gauge.
Man thanks you Awsome video
I want a carb but just can't spend 500 on a 750 brawler
I have a 74 camaro
454 60 over
AFR Enfircer heads
10:1 compression
Hooked headers
The Big Mother Thumper Comp cam
Vac brakes power steering with A/C
200 gph mechanical fuel pump
I want a good street car on a tight budget. I have been gathering parts since summer last year and would like a nice hot rod for the family
Foe trans I got lucky on a 97 4L80e
Spent 89 bucks on a shift kit. Still need a 3000 stall. And need a shift controller.
Thank you! You can make any budget carb work for you as long as you use the right size for the engine. You can find them used all over the place. You would probably benefit from a mechanical secondary carb.
Ya I was just thinking possibly a 650 mechanical secondary
I was actually leaning to a 850 or 750 vacume secondary. But for a budget I'm noticing 650 are cheaper.
Only thing I'm not 100 percent on dialing in a 650 mechanical secondary. All I know is you can adjust the leaver when to open them.
Depending on the 850 it might not be ideal even on a 454 due to the big carb bores. A 750 would make a solid street carb. A 650 might restrict a little bit of airflow but the response down low would be really good.
@@NightWrencher ya a 650 double pumper would be sweet. I was just looking at FST carbs and there pretty affordable.
no real secrets just rambling.
I do tend to ramble :)
I enjoyed your ramblings👍
Lol thanks a bunch!
Just bought a brand new 3310 for $400.By the time I locate all the parts kit and down time..Id rather just buy new and go.
If it works for you, run it. I'd rather buy a used 3310 for $60. Put $100 in parts into it and adjust it to exactly what I need. Off the shelf carbs almost never run perfectly out of the box. Usually IFRs and AP are lean and the secondaries are too rich
You still have a lot to learn.
The metering block you can replace for a few dollars. You did not mention checking that gaskets do not block holes?
There’s no secrets. It’s just common sense.
Common Sense isn't very common
I like your videos and I appreciate how you're trying to help people learn an old style of Technology with modern techniques and things but your explanation of the use of the power valve is completely wrong.
The power valve directly relates to vacuum manifold pressure and the only reason you have the adjustability is to compensate for performance and racing camshafts that produce little to no vacuum 4-6" at idle. That is it! If your engine is running above 16 in of vacuum at idle you do not need change a stock power-valve they don't even make a higher power valve for higher vacuum application it is only to be changed for engines that produce no vacuum.
If you're having issues with hesitation or leaning enriching issues and you try to change a power valve to fix it your only been band aiding one issue and creating another. You do not need and I will repeat this you do not need an AFR gauge to tune a carburetor properly people have been running carburetors for six decades without an AFR gauge I tune carburetors without a AFR gauge and have no problem with riching and leaning. If you're worried about your engine being lean or Rich that's why we check spark plugs, there is always going to be periods of richness and leanness throughout the powerband or when applying the throttle or deceleration that is going to create spikes and drops in your AFR you will never have a consistent AFR throughout the range of the throttle plate.
90% of issues that have to deal with hesitation are the pump not being lashed properly. That is assuming you have the proper timing setup timing and carburetor tuning go hand-in-hand the timing on a carburetor is crucial with EFI you have a lot of wiggle room because the computer will compensate for a screwed-up tune by retarding or advancing timing. You can't forget about timing when tuning a carburetor
I'm going to give you an example of why that is not the case. Lets say you tune your main jets and transition to run at 14:1 to save fuel and run cleaner. Now, say you're idle vacuum is at 22hg but your cruising vacuum is at 16. Lets say youre trying to accelerate to get on to the freeway, by the time you drop to 8hg youre AFR is hitting 15 or more and will cause hesitation. Solution would be to accelerate more to drop the hg to 6 and open the power valve but then you've accelerating more than you want to and wasting more fuel. If PVs were made to compensate for big camshafts, they wouldn't need to make a 8.5, 7.5, 10.5, etc. Originally the PV was called the economizer valve and in fact drag racers don't use PVs at all because at WOT vacuum is at 0 always so theres no point in having a PV. When tuning a carb for a daily driver, tuning from 12.5 to 13.5 could save you at least 2 mpg. The engine, if left at 12.5 would run fine, wouldn't smoke that much and only smell a little bit. Tuning a carb to run clean on the freeway requires other modifications to prevent lean spots when you accelerate but before opening the PV and secondaries. I just went through this on my truck while towing on a 6% grade. I was towing up hill but starting to lean out at part throttle, vacuum was sitting at 7-9 for miles, I could drop the AFRs down by accelerating more but then I would be going too fast. On the next trip i swapped to an 8.5 and I was able to go up the climb with no issues. The problem is youre looking at things through a racing lense but not everything has to be about racing some of us just was a carbed vehicle that runs clean and doesnt smell like gas while we are driving
@@NightWrencher even know where to begin with this you're just spewing out all sorts of data that obviously you learned on the internet and that's coming from your gauges and not knowing how to interpret it for the purpose of these things. The power-valve was not called the economizer that was called your vacuum gauge it was actually a gauge installed in many cars in the 50s 60s and 70s it was a power valve gauge in the sixties when everybody wanted to make power any HP was in but the same gauge was renamed in the seventies during the gas crisis to be called the economizer they're both one in the same thing it is a vacuum gauge and has nothing to do with what is stated inside the carburetor. And Edelbrock / Carter carburetors do not even have a power valve they use metering rods Hollie's are only meant for performance to try and tune them for an everyday vehicle that has nothing to do with performance it's completely useless because they were designed for performance reasons only that is why car manufacturers stop using Holley and started using Carter/ Edelbrocks. Because the average person had a bit of a time keeping a holly in tune they didn't stay in tune they got dirty quickly the vacuum ports kept getting dirty Holly is not an everyday driving vehicle carb is what you're saying it's supposed to be. Truth be told many carburetor experts will tell you that you don't even need a Holley unless your surpassing the 850 CFM airflow range because Carter Edelbrock carbs AR just as accurate and give me the same performance as a holly but they are much more reliable and not as temperamental and finicky to set up on a vehicle. Stay away from Holly's unless you plan on racing them. This kind of stuff is what gave Holley carbs a bad name in the 70s and 80s when people were running muscle cars on the streets that didn't know how to tune them the same way as the guys in the 1950s and 60s knew how to tune them that's why they had such a bad name for being problematic on the street.
I go through this every day, Ive been daily driving a holley carb for almost 2 years now on my LS. The only time I had a hard time keeping a consistant tune was when my old base plate wore out and it was leaking air through the throttle shaft bore. Holleys are excellent carbs. Each system runs independent of one another and you don't have to worry about fluctuations in vacuum to get your tune right. I don't know if you're trying to insult me by saying my numbers are made up, but you can see in my videos that both an AFR and vacuum gauge are always hooked up to my truck. All my adjustments are made based on how I see the numbers respond on my drives. Over 10k miles of daily driving with little to no racing teaches you a lot about tuning holleys. I've towed trailers for hundreds of miles at a time with zero issues and make frequent long trips throught different elevation extremes in my truck without having at adjust anything. Idk why you dislike them so much, but thats fine, to each their own.
@@NightWrencher I suspect I may have the base plate problem. How much play in the throttle shaft is acceptable? What are the symptoms when this occurs? Thanks for your help.
Learn how to read a spark plug.
AFR gauge is better :)
I think you need a new housekeeper. Thats the nastiest work station ive ever seen.
You bet it is, when I bought my house I moved all my carb stuff to one of my extra rooms and now thats where I'm making my carb videos now
Just long arm all that shit into a box, then pick out what you need and toss the rest...
talked a lot, didn't say much
Hard to get past the piled down bench of junk! You talk alot of lingo but your knowledge is marginal.
Exactly, I'd never post any type of informative video with a work bench that looked like that.