I've got a 425 Olds with a freshly rebuilt top-half of the engine. Now after getting it back together, it has what sounds like a backfire w/ a resonant ping coming through the carb. This only happens when you give it some gas and not while idling. Any ideas of what could be causing it?

Thanks-
Tom

 

Hello TWS
My first guess would be you have too spark plug wire's crossed, assumming all valves are adjusted correctly check and double check

 

I HAVE A 70 CUTLASS WITH A 350 ENGINE, DO VALVES HAVE AND ADJUSTING GAP?.

 

Olds engines have no valve adjustment (stock).

 

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