thanks for all the previous help y'all... I just put a rebuilt 2v carb on my 75 mav 302 (after a little engine compartment fire), but no matter what I adjust (idle, timing, idle jets, etc.) I can not seem to get the car to stop hesitating or stalling (when warm) when accelerating normally. If I punch it, there is a little hesitation, but it takes off fine after that. any ideas?!?
Something in the accelerator pump circuit. When you open the throttles you have an enormous air 'hole' that needs a shot of gas to cover up until the carb catches up... to put it simply. If the accelerator pump doesn't add enough fuel or put the fuel in fast enough you will bog, hesitate, or even stall. Some possible causes: (some but not all) Leaky accelerator pump or hole in diaphram, leaking fuel totally out of carb onto intake when the throttle is pressed. Stuck pump, no fuel pumped at all when throttle pressed. Stuck check ball, no fuel getting into pump. Check ball gone, this would cause the pump shot to shoot right back into carb bowl. Plugged squirters... less likely. I'm sure I am forgeting some, but the pump system is small and simple. Should be easy to track down. Dave Edit: I see by re-reading that you just went through the carb... Did you put the accelerator pump check ball back? (sometimes they use a rubber 'umbrella' instead of the little ball)
On the other hand, is your choke set correctly? Make sure the plate on top of the carb is wide open when warm. If you are stalling and idling rough you should check for vaccuum leaks. Did the car have the problem b4 you replaced the carb? Or did the prob only show up after you rebuilt the carb? Your 75 is probably electronic ignition, but if it is not, check your points.
Your idle is adjusted to lean. A slow advance of the throttle will not cause a very large quanity if fuel from the accelerator pump in any event. There needs to be a smooth transition to the intermediate fuel system. These carbs are known for this problem. The idle needle controls the fuel added to the fixed air passage. This is a reverse of the way most carbs work. Adjust for the smoothest idle then go a little richer till the problem is gone or minimized. A vacuum gauge would be helpfull. The factory did this to hold the adjustment to within narrow limits, for emissions reasons, so the user could not get it to far out of adjustment.
I couldnt help but notice that you said you had a "small" fire. Just an idea, but do you think the fire might've burnt a vacuum hose or line? Vacuum leaks are pesky--hard to find, and will really ruin your day. Just a thought.
Geez I guess I'm not the only one with this problem. My Mav was also hesitating and staling and overall running like S**T after I rebuilt my carb. Best thing to do is to first recheck your work on the carb (making sure you didn't install the acc. pump backwards). Then make sure you replace the carb to manifold spacer on right (flat side up) with new gaskets. Be sure your manifold spacer is still in one piece with good contact to the manifold and carb. Put everything back together start it and check for leaks with a small hose up to your ear or some carb cleaner around the carb base. If you hear any change in idle when spraying it with the spray then you've found your problem. A leak. Your PCV valve at the back of the carb might be leaking. Check and make sure you put it back on the same way you took it off. If that's alright then my guess is that you are just running way to lean. When its running like crap put your hand over the carb and if the idle smooths out you need to turn the mixture screws out. I started at 2 1/2 turns out and went from there. Get yourself a vacuum gauge and learn how to read it. Go to this site for that, http://www.centuryperformance.com/vacuum.htm Anyways good luck and I hope you find out what is making it run like crap.
