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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1986GMCSierra on February 26, 2015, 10:36:39 pm

Title: Exhaust Backfire
Post by: 1986GMCSierra on February 26, 2015, 10:36:39 pm

I have a 1986 305 GMC C1500 i have the rochester 4bbl carb and i have a backfire problem..... for now the exhaust is set up like.. stock headers to catylitic converter to pipe then out, so pretty much straight piped..... i took it all apart and ensured there are no leaks... i cant seem to track down the backfire problem.. the idle is also higher than normal but that is juat my judgement by sound because i dont have a tachometer...

Title: Re: Exhaust Backfire
Post by: rich weyand on February 26, 2015, 11:28:29 pm

I take it you mean after-fire -- out the exhaust -- and not backfire -- back through the carburetor.

I got afterfires and loss of power in my truck when the distributor, which had not been properly clamped down, moved retarded.  I checked, and I was at 4* AFTER top dead center.

Title: Re: Exhaust Backfire
Post by: 1986GMCSierra on February 28, 2015, 07:38:42 pm

Quote from: rich weyand on February 26, 2015, 11:28:29 pm

I take it you mean after-fire -- out the exhaust -- and not backfire -- back through the carburetor.

I got afterfires and loss of power in my truck when the distributor, which had not been properly clamped down, moved retarded.  I checked, and I was at 4* AFTER top dead center.

yes i mean afterfires.... i will take a closer look