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Ziggster · 03-07-2026, 08:37 PM

Vacuum leaks can come from any number of areas. If the throttle shaft is loose, air can sneak past it and the shaft thru holes in the base. Warped diecast pcs can also be a source of leaks. Of you’re getting a back fire, chances are the PV seal has been blown resulting in gas leaking straight out of the fuel bowl into the intake.
Has it been rebuilt recently? I’ve rebuilt a couple recently, and there was lots of debris/dirt/etc in most of the fuel passages in the towers/brass needles. Also, you might want to check the accelerator pump function.

03-07-2026, 08:37 PM	#2
Ziggster Senior Member Join Date: Aug 2018 Location: Ottawa, ON Posts: 1,373	Re: Holley 94 Carb on 34 engine Vacuum leaks can come from any number of areas. If the throttle shaft is loose, air can sneak past it and the shaft thru holes in the base. Warped diecast pcs can also be a source of leaks. Of you’re getting a back fire, chances are the PV seal has been blown resulting in gas leaking straight out of the fuel bowl into the intake. Has it been rebuilt recently? I’ve rebuilt a couple recently, and there was lots of debris/dirt/etc in most of the fuel passages in the towers/brass needles. Also, you might want to check the accelerator pump function.