Okay going to try to explain this as short as possible. I have an 86 Iroc Z-28. We changed the carb on it from a quadra jet over to a Holly. This is where my troubles start. When the car is sitting in park idling it seems to be flooding out. When you attempt to drive the car it seems to be starving for gas. The engine wants to stall out you have to play with the gas when you reach a cruising speed to keep the car runing? Any help as to what could be the problem would be much appriciated.

Ashley

 

I see you are a new member. So first of welcome to TGO. If you post your question in the carb section, they will be able to help you more then everyone here. Maybe a mod can repost this in the right section for you? I unfortunately can't help you at all.

 

First thing ide check is your fuel pressure as i measured an old factory pump producing like 3-4 psi when holleys need like 6 if im not mistaken. Did you swap the intake manifold to put on a square bore holley, use an adapter, or get a spread bore holley?

 

Used an adapter plate. Just bought a new fuel pump yesterday. Will be putting it on today. They said that the fuel pump I bought should be enough for the new carb. Could the floats in the carb be set wrong?

 

Swap out the computer controlled distributor to a vacuum advance when you replaced the carb?

 

Its plausable that the floats could be set wrong but especially if its a new carb kinda unlikely. If you do install a new pump make sure you use some kind of a regulator on it unless its self regulated. Too much pressure and too little will make the car never run right. Also what part number carb did u get?

 

Yeah we did but still have the problem

 

Its not a brand new carb just new to me. Its one that my boyfriend had on his toy, until my car started giving me problems. The carb seemed to be fine when on his motor.

 

Well if it was known to be running on another your boyfriends car then no worries then. The carb should be ok atleast unless it was dropped or something or sat in a basement full of gas for a few years. Ide be curious to see hoe it does with a new pump and regulator.

 

You probably have the wrong power valve in the carb, it's easy to get to just inside the metering plate past the float bowl.
They come in sizes 2.5"HG up to 10.5"HG (opening vacuum). They are available at Jegs for 'bout $10.00 you will also need Gasket kit $5.00.
Go to Holley's website and look up your model carbeurator, and they will have complete tuning instructions for your model. It will tell you the process for determining the proper size...LOL

 

STOP!

Answer this question.

If the answer is "No" or "I don't know", you need to change the distributor.

No more talk about floats or fuel pressure or fuel pumps until this question is answered.

 

Most carburetor problems can be traced back to ignition. Always make sure the ignition is dead right before attempting any carb tuning.

If you swapped this carb in place of the stock computer controlled qjet and did not also swap the computer controlled distributor out, you'll never get good performance out of it because the computer controls the timing advance (and isn't anymore with out the feedback from the carb).

You may also need to install some alternate means of locking the torque converter. See the sticky on top of the carb forum. Running without lockup can significantly shorten the life of the trans. Trans rebuilds round here start at ~$1200.

There's a Columbia based Fbody ground at www.scfbaonline.com. They get together once a month or so and try to spread the fun around the state with some meets planned upstate too.

 

Didn't get the pump on tonight. Should get it done first thing in the morning I'll let you know how it works then.

 

I'll look that up tonight after I finish answering all my replies. Thanks

 

I changed the distributor 3 times I have a Accel HEI on it now. That was part of the problem in the beginning when we first changed the carb.

 

Not sure I'm following you on the ignition thing. Can you give more info on making sure this is right.

 

what size holley is it ? have you checked the float level with the plug out of the side of the carb , if fuel runs out theyre too high adjust them.if you cant see any fuel when looking thru hole raise the float level until the fuel almost starts to run out. have you tried adjusting the screws on the sides, run them all the way in and turn them out 1-1/2 turns and go from there turning them out a little at a time,jimmy

 

Assuming you have a correct vacuum controlled dist: Check your timing at idle and with the advance all in, ensure you're getting the proper ignition advance at the proper rpms. Check condition of your cap/rotor/plugs/wires. If any of this needs to be replaced do it BEFORE trying to make any carb adjustments.

Ignition timing sets the rhythm by which all other components must be adjusted. If it's off, no amount of fiddling with the carburetor will make it run better.

I suspect you've overcarbed the motor but if it were mine I wouldn't start fiddling with the carb until I'd put a timing gun on the ignition. It's kinda a rule.