Holley Carb: Accelerator Pump Set-Up & Tune (CARB BASICS PART: 2)
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- Опубликовано: 7 сен 2024
- Discussing the Holley accelerator Pump Set-up and tuning. you should fully understand how to adjust your accelerator pump after this video. i use a wideband AEM o2 gauge. they are on ebay for 150 and are very accurate.
Excellent explanations.
Always adjust the accelerator pump linkage first before you do any cam or nozzle tweaks, and like you said, readjust after any tweaks.
The .015 feeler gauge should make the accelerator pump arm move as it slips through between both arms at WOT.
Hey buddy, thanks so much for your vids. I forget how I found your channel (maybe a FE search waz back) anyway I just think your basic dumb downed videos ( not meant to be mean) make it so easy to understand the simple facts. I rebuilt my first 4160 and I watched your vids over and over... and many many others. Long story short.... rebuilt, installed my first carb on my own! motor started after a bit of timing (so SUCCESS) ... After it ran I needed to tune ALL of it.. it ran but it needed love... back to your channel.. I did EVERYTHING and double checked EVERYTHING... no matter what couldn't get the accelerator squirter to squirt. Remember this is my first ever attempt to try this. At this point I'd give up and bring it someplace.. I mean it started, ran and could drive and show it off a bit but it just ran like shit. I could always just blame Holley:)... I spent a couple nights watching vid's and jumped in. On and off, on and off... maybe 5 times... ended up I had to take the front apart and check everything. Gaskets,passage etc.. ended up being the check needle before the squirter. When I cleaned it I musta never got it out or I did and the first bit of fuel was real dirty. Anyway... every time I hit a wall I checked out your vid's.. and others but, thought it be nice to know your vids are really good. Happy Holidays Buddy
Gonna do some tuning. Thanks for the help! Keep making these videos they are surely the best on Holleys Carbs.
Great information, and you didn’t say that word once!!! Haa ha , just kidding, and I will keep learning, as I have, I think, a 780 vacuum secondary Holley on my 71 Camaro and it’s running rich, so I will get the o2 sensor and vacuum gauge to help tune , with what I have started to learn from your videos. Keep up the great work
Thanks
dave colquhoun learn how to read your spark plugs too.
A light chocolate brown is a perfect mixture. Light tan like everybody touts is too lean.
lever and accelerator pump arm...i'll have to look at mine and see if i cant figure it out...thanks for pointing me in the right direction.
+james myers Hope it helps, make sure you dont have too much of your transfer slots exposed
ThunderHead289 i may go ahead and attempt to swap intakes while im at it and put on my air gap. I was wondering if a little port work to my intake makes a difference ? Do you think its worth it or is it a waste of time ? Or should i just throw it on as it is ?
port matching makes a solid difference, but with your intake, you dont necessarily want to have smooth runners as it hurts fuel atomization.
ThunderHead289 cool thanks
I have a 73 302 in a 79 f100 with a 600 Holley vacuum secondaries and in turned and tweaked the mixture and can't figure out why I can step on it and it bogs bad but I can let off and hit it again really quick and it takes off great any help would be appreciated it has a 262/272 cam duration jegs cam and lifters its board 40 over timing set to 10/12 I don't know if being a dual plain intake would make a difference I have learned alot from your videos thanks
Great video, if I want to use the number two do I also use the number two on the cam or a place, the number one on slot two
800 /1000 rpm will slide with a manual / automatic be big bang city when you put it in gear .... Im running a 500 cfm 4412 2bbl on my 69 390 50 cc pump on the Holly sizing chart it was the right carb the 350 cfm would also work but 500 sounds better ...going to try these tips thanks ....
Awesome video mate Cheers for the info
Hi Luke! I have a Holly 4160 750cfm and vacuum secondary no vacuum choke. Does the same rule apply for adjustments? Thanks, I know this is an older video, hope you see the comment. Respect and thanks from Motown.
I bought an aftermarket 950 proforma main body and base plate and tried it on my 428 fe engine and it's drowning the engine with too much fuel. I thought it was the fuel pressure overunning the needle and seat so I put my 750 holley back on the engine and it didn't do it. Then I put the stock holley baseplate back on it and the same thine happened. Do you think it's possible that the throttle body could have been machined wrong? I tried changing out all the other parts with the throttle body to no effect. Nothing fixed it but the part isn't under warranty any more and I can't send it back. What should I do. I have been racing for 20 years and never seen this issue.
Hello i have a 750 cfm summit carb but its idle 1500 then drops to 600 then back to 1500what could that be
This is real great stuff, but I left a message with yourself about a week or so ago asking about when it is to the extreme of needing the choke to get it started even from hot and having to set the choke flap at a curtain gap of just open of about 1/4"? You may have replied on here, but I haven't managed to suss this totally yet? Anyway I will keep looking on here and now I've sussed your not the other Guy Randy as well that may help? So this video is great stuff and the others I've seen too.
Tyrone Savill you’re perfectly describing a vacuum leak. You need your choke closed in order to richen the air/fuel mixture because the vacuum leak is providing too much air causing a lean condition.
The choke compensated for that. With the engine running, spray carburetor cleaner around every vacuum port, vacuum hose, carb base and intake manifold gasket. When the carb cleaner hits the leak, the rpm will raise slightly. You’ll hear it.
Replace old hoses. Tighten your carb down good and finally, replace any leaking gasket.
You cannot tune your carb if there is a vacuum leak. Impossible.
Dumb question, but you mention pump cam position one and two? How is this area changed from one to 2? My bbc has a larger duration solid cam and surges at part throttle, it won't stay running at 850 rpm only 1000
Most cams have screw holes to change the orientation. I am not familiar however which hole to use.
Holley states, Squirters first before cams, and also clearance at WOT of .015 on lever to prevent diaphram damage and no slop on idle, WHy are you backwards ?
+MR BILL Purcell your cam needs to be set for your idle rpm range. everytime you change your curb idle screw or your pump cam setting, the acc pump lever has to be adjusted. a pump cam is for finer tuning of the acc pump. most all street engines run great with the 31 holley squirter and just need to be dialed in with the proper pump cam.
+ThunderHead289 MR BILL is correct about the WOT .015 clearance to prevent diaphragm damage; at least according to the GMC service manual.
Do the cams wear out over time?
i didnt disagree with him there, they definitely could over 100k miles, but a little grease would prevent it.
Do you suppose a leaking pump diaphragm would equal poor performance? A screw dropped out and I can see fuel swelling around the pump and float bowl. Argh... Thanks for the videos btw. ☺
honestly, unless your pump shot is shooting out the side of your carb, it should not cause poor performance. fire hazard yes, but the performance should still be there. im redoing the top end of my f100, and when i do i plan to make a tuning from scratch video series on setting up a carb and ignition for consistent performance and drivability.
nice job
With regard to your mention of idle speeds, I wonder if you could give me an example of WHY one might have the idle at 1000 or more. Thanks
+Anthony Wayne usually drag cars or something with a pretty lumpy cam. Many of my cars idle right at 900.
Ah I see. Thank you.
It's funny, I've pretty much gotten used to my off idle bog when accelerating from a stop with my SBC 383 dart pro1, Z gap ringed, 10.25:1, comp big motha Thumper (I bought this cam before I knew better), full roller motor with a Holley 830 annular. I just wind it up to 1500+ to give it a fighting chance of taking off from a stop without bogging or stalling. You give me hope that I can tune this beast (69 c3 4speed).
Do you think I have the right carb for this motor?
That's getting pretty large to where it might not have good road manners. If you drive it on the street, I'd prefer a 750. If you'd like, take a look at my recent uploads. I subscriber sent me a carb, and I tuned it on the bench and on an engine all on camera. Might give you a good idea of some things to look for. I'd also recommend a summit brand 750 vac secondary or possibly a double pumper depending on your vehicle
ThunderHead289 You think? From what I was told by the guys at SoCal Speed Shop, an 830 annular is the equivalent of a regular 750. the car runs great everywhere but just off idle and when just barely giving it gas at lower RPM at say around 45mph give or take. I was thinking that 4" of vacuum at idle could have something to do with it. I'm a noob when it comes to carbs but enjoying the learning process.
now how about a vid on the different accelerator cams with some corn feed girls in the background :) Just playn... but I'm serous about the cam's vid... thanks again
So I've got a holley 600 in my f100. I've done the cam (orange) and put it on 1 since I idle 550-600ish but it's still falling on its face. I haven't been able to do anything with the squirt nozzle yet. It's a reman carb from Oreillys. Is it possible it was remanned with the wrong nozzle?
I know it's an older video, but I'm hoping u can still give a fellow iowan some advice
It its absolutely possible that the re-manned has a nozzle not optimum for your set up. Brand new from Holley will not always be optimum, which is why you tune by ear after taking out slack in the lever (.015 feeler gauge), then try a nozzle 3 sizes up as @ThunderHead289 suggest. The snappy response when twitching the throttle while parked is how you will know that the final nozzle size is dead on. Ensure engine is fully warmed up before doing any idle adjustments.
Had a question on selecting cam hole 1,2,or 3, are we talking idle rpm in gear or in park? My idle is around 800 in gear and 660 in drive that's the lowest it'll go? Any help! Thanks
I'd idle her at about a grand in park. Auto cars are a bit more tricky. I'd also set your pump cam position itself based on your in gear rpm, which would be position one.
Position 1 for that idle. 1000 rpm for a stock motor and torque converter is too high. If it idles at 660 in drive, you definitely have a stock cam and a low idle is perfectly fine. Position 1 on the cam will give you an instant shot of fuel and prevent a hesitation.
If you idle your stock low stall speed torque converter at 1000 RPM you’ll be mashing on the brake pedal at stops to keep it from rolling.
5:40 Squirt nozzle
So ? If my excelerator pump is torn or messed up my car wont run proper ? I have a 1985 mustang carburated.it idles great can rev motor good...does not drive down the road...its like im jerking the throdle but im not ?this was a working carb and something is wrong now and i cant figure it out
Thomas -
Refrain from adjusting the carb if it ran well before. It could be one of a few things. Make sure that when you blip the throttle by hand, fuel comes out the boosters. If it does, the pump is good. Sounds like it is either a fuel delivery issue or an ignition issue. Make sure your fuel pump is working properly and that you have a clean fuel filter. Seems like under fuel demand it is leaning out. Have a look under the cap and make sure the advance hasn’t froze up on you - if you can turn the rotor a few degrees by hand and then it returns to its home position, you are good there most likely. Remove the vacuum advance, and suck on the air line, if the body again advances, your vacuum advance is in good shape.
ThunderHead289 thanks for the information..its very apperiated.
Thomas Gadsby no problem, I run a Facebook page for stuff like this. If you search thunderhead289, you will find it 👍
I NEED TO ADJUST MY SEMEN SQUIRTER, BIGGER CAM??
Pump shot is wrong on that carb