[1quiknova]

I have a 71 nova w/ a 357 sb, rpm air gap, .490lift comp cam and most importantly to the question, a holley 750 4160 carb. When I get into the gas hard and let off the car usually stalls? What could be causing this? running to rich?

[78 monte]

Black smoke out the tailpipes??Pull the plugs and see after a full throttle blast.

[1quiknova]

no, there is no black smoke. If I crack it, not even wot, then let off completely or get on the breaks, it usually stalls, but it always starts right back up.

[streetfytr68]

Maybe you are emptying the fuel bowls?? What do you have for a fuel system?

[1quiknova]

holley 8psi mechanical pump and my fuel pressure guage reads right around 8psi.

[killerformula]

sounds like too much fuel, is your power vavle open? Where are the floats? Are you sure your needle and seat are functioning properly?

K

[1quiknova]

I checked my flots, they are right on, and i set the idle mixture with a vac. guage and they are good. Now as far as the power valve goes, how do you tell if it is open? By open do just mean is it blown? i know how to tell if ti's blown, but i'm not sure what you mean?

[bracketeer]

I would say your carb is too big. You should be running a 650.

[Siggy_Freud]

Originally Posted by bracketeer

I would say your carb is too big. You should be running a 650.

Even so I cant imagine that it being to big would result in the problems he's having. Id guess that there are lots of people running a similiar size carb on such a combo without the stalling issues. Just a thought.

[engineczar]

Sounds like it could be one of two problems. The float level in the back bowl is too high which is causing fuel to push out the vent and into the engine when you let off or the timing is going way off when the vacuum comes back up when you let off after a hard pass.
Check the back float level and/or try running it with no vacuum advance, just mechanical advance.

[1quiknova]

The timing issue sounds like that may be, b/c at first after I put the motor in the timing wouldn't come back to it's original place when advancing it with the timing light, so we replaced the bushings, which were trashed, and put lighter springs in it, maybe go to the heaviest spring?

[GoneNova/406]

you can go to mortec.com and http://www.bob2000.com/carb.htm and you should find the help you need.

[1quiknova]

With my 8psi holley mechanical fuel pump I read 8psi on the fuel pressure guage, I know it should be between 4-7, so is this too much? And could this be causing my problem?