I have been tuning on a Holley 750 4150 HP vac sec (80529-1) carb http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY%2D0%2D80529%2D1&N=700+306299+4294785104+115&autoview=skuforever and I get it running good and the next thing you know it is running bad again. Problems move all over. I'am running this car on the street and did not know when I bought this carb it was tuned as a race carb. I have tried everthing and I'am tried of messing with this carb and want to replace it with something else. I think this carb is a lemon. What carb should I buy? I like to go fast. Engine is BB396 bored 30 over, airgap intake, Canton 1" carb spacer, Edlebrock aluminum heads, Crane 1.7 roller rockers, headers, MSD distributor, Comp cam 274/286 adv. duration .552/.555 lift cam TH350 trans and 2400 TCI stall converter.

THANKS RAYZZ MY CAMARO LIKES MY MONEY

thats not a double pumper carb

Whats a double pumper carb?

I doubt your carb is a lemon, usually when problems seem to move around it's from not tuning the right circuit. Even though you don't give any clue to what problems you are having, your frustration level has got to be the biggest problem. Start over by putting the carb on your work bench and setting the carb back to the factory spec's as it should have been right out of the box. Call Holley if you need help getting the factory spec's and here are two links, the instructions for your carb and if you are not confident you understand your Holley the second is to the sites tech reference area with 3 basic Holley articles.

http://static.summitracing.com/global/images/instructions/hly-199r10016-2.pdf

http://www.camaros.net/techref/series_2.html

Whats a double pumper carb?
Mechanical secondary carbs have an accelerator pump on both sides of the carb, one for the primaries like your carb and one for the secondaries. Thus it's refered to as a double pumper. Your carb is a 4 corner idle vacuum secondary carb.

Carb is only 3 years old with only 3000 miles on it. I had it rebuilt just to see if anything was wrong no problem found. I have done lots of timing changes, Pump jets, pump cams, power valves, secondary springs and played with float levels. It has always ran good on top but bad off idle. Carb runs the best it ever has but it still bogs real bad and almost dies when you give it gas in first gear at slow speeds or when cruising in third gear. Above 2800 RPM it runs good. I have tried all the combination I can think of. Now I just want to get the car running good. Money is not a problem. What carb should I try? If I get it runnig good I can get back to working more.


THANKS RAYZZ MY CAMARO LIKES MY MONEY

Any Holley you buy Ray is going to have the same problems if you make adjustments to the wrong circuit. If you are really intent on benching that carb give a Street Avenger 770 a try. It's also a vacuum sec carb but is not a 4 corner idle and has a choke.

Or HP 750 Holley ,very nice out of the box unit,I have one on my motor...Happy Motoring

Or HP 750 Holley ,very nice out of the box unit,I have one on my motor...Happy Motoring

That is what he already has...

Holley had some recalls on a few carbs about three years ago. I had a 760 with vacuum secondary and I have a big inch small block that did well over 500HP at the flywheel and though I left some HPs on the table the engine runs awesome all across the spectrum for everyday street driving. I just put a HP950 on my car and it picked up , I couldn't resist but I did sacrifice some drive ability but nothing that bothers me too much.... right now

Also.. I let this car out of my hands one time to have someone do work on it because of time constraints I had... they messed up my fuel line twice . The car was running poorly because the fuel was getting heated up by the lower radiator hose to the point the car locked up on me one time.... I fixed that problem and the car is running like it used to with no problems. Check the rest of your fuel delivery system too.

You could take it to someone that rebuilds/tunes carbs for a living that is local to you. If you really are convinced that you have a Lemon and don't want to spend anymore money on it, consider a 770cfm Holly Street Avenger with Vac secondaries and an electric choke. Summit sells them:
http://store.summitracing.com/partdetail.asp?part=HLY-0-83770&N

Also here is Holly's carb recommendation tool:
http://www.holley.com/applications/CarburetorSelector/CarbSelection.asp
Which recommends a 750-770 carb based on street use, 6k max rpm and mild modified.

I,ve rapped the fuel line at headers and the line were it goes between water pump and block. New fuel lines, fuel pickup and tank. I have tried different timing spec's but timing is at 14* intial 36* total all in at 3000 RPM now. Crane adjustable vac can, limited to 8* vac advance.
When I stomp gas at 1800 RPM the car will die.

THANKS RAYZZ MY CAMARO LIKES MY MONEY

Stupid thing to say, but a box stock 3310- Holley should be just about perfect for your application!

And if you want good driveability plus gas mileage install a stock 750 Q-Jet or one of the 800 cfm one's off the 455" BOP engines! It really doesn't matter b/c, a Q-Jet being a vacuum secondary, will only allow the engine's secondaries to suck as much as the engine need's under load!

Fwiw, my Strong-Arm 406 SB has a 750 Q-Jet off a 403 Olds if not mistaken, it's been years.

pdq67

That is what he already has...

Can't help that ,out of the box for the money you can't go wrong 4 corner I ,works good with my 234/242 Dur. Cam 112 cl,800 rpm idle if it aint tuned or got a close factory settings ,when verious things are changed and no gain IMO you should go back ,to fac set and then ty another or ya never know where you are at...ol backyard dude we use to think was nuts ...but wasn't ...we listened and got my pals GTO to run 14.0 i think back in 76 with tuning headers holley 750 spread bore ... sometimes you half to start over with fac. setting and, start the parts change again...Good luck and Happy motoring

Hlley was a great brand for a race car YEARS ago. and they ARE made to fine tune a race car. But if you didnt know this holley went bankrupt 2008 so there parts may not be of the best standards. If you have a daily driver, like me, id advise an edelbrock carb. theyre simple, and they run very smooth. and the price is right. :thumbsup:

The carb you have should run fine on your application, but you do need to make some adjustments. What is happening is that your air speed through the carb at low rpms is not enough to pull fuel and atomize it well, thus it bogs. As you have it set up right now it probably has a tendency to foul the plugs which would cause erratic operation. First thing you should do is readjust your timing to 18 degrees intial with about 36 total, next go to the lightest springs so that your advance comes in as quick as possible, 3000 is too late, closer to 2000-2500 would be much better. Also try removing your spacer or if you have to run one use a 4 hole spacer. An open spacer will just slow the air speed on the low end aggravating the problem you already have. Once you have your timing set right check your butterfly adjustment in relationship to the transfer slot, should be no more than .020 of transfer slot showing below the butterflies at idle. If primary side is too far open, then slightly open secondaries so that primary side can come back down to where it should be. You may also need to go to a bigger squirter nozzle and/or shim the accelerator pump arm spring, but only if it still bogs when hitting it hard. Put a fresh set of plugs in it after timing and idle circuit is adjusted right.

Hlley was a great brand for a race car YEARS ago. and they ARE made to fine tune a race car. But if you didnt know this holley went bankrupt 2008 so there parts may not be of the best standards. If you have a daily driver, like me, id advise an edelbrock carb. theyre simple, and they run very smooth. and the price is right. :thumbsup:

What's Holley's money problems in 2008 got to do with a carb that is 3 years old? I would have no problems daily driving either of my Holley carb'd cars and if you research it, Holley makes carbs with chokes designed for street use as well as race carbs... We really need to get past this brand loyality thing and acknowledge it's what you get use to and are comfortible with...

There is no better carb for the street than a Q-Jet. With the right modifications, a properly tuned Q-Jet can and will outperform ANYTHING.

This carb should work great on your engine if it's tuned right. If you don't know how to adjust the idle mixture screws then having a carb with 4 screws makes it twice as difficult.

How much vacuum is your engine pulling at idle and what is your idle speed?

It looks like you have a pretty stout cam in the engine. This may give you a low vacuum reading at idle which makes adjusting the idle mixture more difficult.

If your engine is stumbling or hesitating off the line, you may need a larger accelerator pump squirter.

Holley has a great "Installation and Tuning DVD" that lists common problems and explains how to correct them. Holley's part number for the DVD is #36-378. Order it from Summit or call Holley direct. Their web site is www.holley.com.

You might also remove the spacer under the carb until you get it straightened out. The spacer can affect the vacuum signal to the carb idle circuits and can contribute to the hesitation under acceleration that you indicated.

If you have had backfiring, you may also have blown the power valve. The video talks about this too.

Good luck.

Rayzz,

Lots of good info in this thread. Have you checked your vaccuum advance? If you have a factory type it may be the culprit causing your headache. When you stand on the gas pedal the vacuum may go down significantly and the timing advance doesn't come in like it is supposed to.

Just an idea, and a cheap fix if that is the problem!

There is no better carb for the street than a Q-Jet. With the right modifications, a properly tuned Q-Jet can and will outperform ANYTHING.

Exactly why when I go to the dragstrip I never see a street/strip car (nor a strip only car) with a Q-jet. Not saying that a properly tuned Q-jet isn't good - but to say it will outperform ANYTHING might be a bit of an overstatement.

I'm running a Holley Street Avenger 770 on my 383 with a comp cam 282 hr roller cam with Trickflow heads. The engine is freshly built and was rated about 450hp and 480 torque from M&R engines. I had nothing but problems in the beginning with getting the car to run and idle consistantly. I tuned it and retuned it and went through 3 sets of plugs. :confused:THEN, after alot of head scratching and some "words" I realized that I somehow blew the fuse for the electric choke!! Once I replaced the fuse to the choke the car started to run consistanly and "smooth as silk"!! The 770 Holley Avenger really is a good carb, operator errors aside!:D

what BPOS said X2.

I'd really like to see what vacuum you have at idle.
I know on some edelbrock carbs if you have too low of engine vac. the metering rods don't do their job and at idle you will be idling on the circuit that is supposed to be open when you nail it (low low vac and high load) I know holley does not use metering rods but maybe it is a similar problem.
Don't know much about carbs, especially holley.
Just my 02.
Borrow a buddys carb that is a few sizes smaller and see what that does, but I vote your idling pig rich (from low idle vac?) which explains why you have to give it about 3k before you can wail on it.