Backfire under loads - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dead Parrot · 08-15-2018, 08:52 PM

Possible exhaust restriction? Does it still have the riser valve? Is it stuck shut?

Since you replaced the intake and carb, the source of a lot of hidden vacuum leaks went away but might check all the hoses anyway.

What are the plugs telling you? With the new intake, carb and now decent timing set, the plugs should tell you if any of the cylinders are out of sorts with the rest.

2nd on trying more timing. Since the engine was modified by a PO, possible the timing marks are lined up off.

08-15-2018, 08:52 PM	#4
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,809	Re: Backfire under loads Possible exhaust restriction? Does it still have the riser valve? Is it stuck shut? Since you replaced the intake and carb, the source of a lot of hidden vacuum leaks went away but might check all the hoses anyway. What are the plugs telling you? With the new intake, carb and now decent timing set, the plugs should tell you if any of the cylinders are out of sorts with the rest. 2nd on trying more timing. Since the engine was modified by a PO, possible the timing marks are lined up off.



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