Exhaust Backfire

[1986GMCSierra]

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...

[rich weyand]

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.

[1986GMCSierra]

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