Hesitation problem

I have a new carb (34 PICT) with a new dualport running an old dual vac dizzy with a Compufire ignition. The car seems to hesitate under acceleration especially in 1st and 2nd gears. The hesitation is especially noticable when the car is cold. I adjusted the timing at idle with a timing light. I also adjusted the carb but I still have the hesitation problem. My question is what could cause it? One thing I wonder is if I adjust the advance the RPMs increase. If I then adjust the carb to lower the idle it throws the timing off and I must advance the diz again. At what point am I really at correct advance??

--Dan E

Reply to
Braukuche
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First, check both vacuum diaphragms by sucking on the hose and watching the advance plate. Must go to the stop and stay there when you plug the hose (with tongue).

Make sure the throttle plate closes fully (but not to jam).

If you get the correct 5 deg AFTER TDC initial setting with strobe timing light, watch the advance as you open throttle from idle. I don't have an exact figure, but the first few hundred RPM increase should produce a whopper timing advance well into BEFORE TDC territory.

If the timing seems right, check that the manifold preheat pipe gets hot at *both* ends after a 1 mile run around town. If only hot at one end, it's not working. No heat means hesitation.

I'm sure you already checked, but make sure the accel pump begins discharging as soon as the throttle moves.

Speedy Jim

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Reply to
Speedy Jim

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