I have a 71 Chevelle with a 383 ci engine, Holley 4-barrel and electronic ignition (no points). When it is in park or neutral, the engine revs up real fast. However when it is in gear (under load), it hesitates quite a bit before revving up. Timing issue?

I would start with the timing, what type of dist? does it have vacuum advance?

Not sure what kind of distributor, but it does have vacuum advance.

TTT- Sorry

You might want to try a new set of plugs. Many times they wont fire under pressure or load but will idle fine. Just a thought. FYI

You might want to try a new set of plugs. Many times they wont fire under pressure or load but will idle fine. Just a thought. FYI
I agree when you get a miss under load its usually ignition, try the normal tune up stuff first like plugs , wires etc.

Dave

What is your initial timing? Total? If that is good, then a larger squirter usually does the trick.

Other than the above, could be lean.

Just got back from a drive in the Chevelle. I found that when in gear if I floor it, the engine almost dies. If I give it a little gas and then floor it, it revs up fine. Accelerator pump problem or timing advance problem? Something else?

Accelerator pump problem it sounds like, I would check both.

Dave

For me, it was timing. I advanced it a bit and the hesitation went away, but was harder to start

I had a similar issue with mine, HEI distributer, it turned out the mechaical advance was sticky and some of the time it was staying advanced

Just got back from a drive in the Chevelle. I found that when in gear if I floor it, the engine almost dies. If I give it a little gas and then floor it, it revs up fine. Accelerator pump problem or timing advance problem? Something else?

The only good way to know what IS wrong is to know what is NOT wrong. Like already suggested, check ALL systems. If all components (plugs, wires, rotor, cap, accellerator pump shot, etc.) check out then you can look elsewhere. What is your total timing and how soon does it come in?

Sounds like its not getting a shot of fuel when it needs it early. Is it a Holley? If so its an easy fix either by resetting the accelerator cam (or using a different one) or replacing the diaphragm. You would have to lift the carb to get to the screws though.
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Dave
TC #4334
ACES #8193

Just got back from a drive in the Chevelle. I found that when in gear if I floor it, the engine almost dies. If I give it a little gas and then floor it, it revs up fine. Accelerator pump problem or timing advance problem? Something else?

Now you got me thinking. Make sure the advance is not froze up. Take the cap off and make sure you can move it by hand.

Have had problems with the advance sticking - guess I will buy a new distributor. Thanks for all the advice.

Have had problems with the advance sticking - guess I will buy a new distributor. Thanks for all the advice.

Why buy a new one when you can replace the weights, little plastic bushings, and springs? Unless your pins are badly worn? An advance kit costs $8 from any performance place...Summit, Jegs.