backfire question

[65notch]

i just installed a new cam in my 289 and i have an exhaust backfire during shifts...manual trans....when going to shift, i push in the clutch and the backfire happens a two or three times while the rpms drop....this only happens during moderate to heavy acceleration. if i granny it, she doesnt pop. possible timming issue?

 

[65notch]

i was reading in other posts about an exhaust leak causing a backfire...how does that happen?

 

[Dothang67]

I have the same issue. From what I heard, when there is a leak, the exhaust system sucks air where the leak/gap is and thats what makes the noise. I do need to tighten the headers bolts to see if that is the problem.

 

[headgrinder]

exaust leak and backfire

If you have an exaust leak it can allow air(oxygen) into the exaust flow.If there is unburnt fuel in exaust (running rich) the air/fuel can ignite in exaust causing backfire.Be careful if there is enough fuel it can also cause a fire. Good luck

 

[krallman]

did you install a stock style cam or something with a little more performance. If you installed one with more lift and duration your vavles are going to be open longer with means the timing that was set with what you had in it before isnt going to be right for what you have now. have you tried adjusting your timing since the new cam. try advancing it and see if that does anything.

 

[rbohm]

a lean idle fuel mixture will also cause afterburn(backfiring through the exhaust).

 

[57fairlane]

if it backfires when you "get on it" vs baby the car, it more than likely is retarded timing. Checking it with a light should take all of 10 seconds . . .

 

[65notch]

yes i installed a new cam, but also timmed the engine to edelbrocks standard specs. im 14initial and 34full i believe.