backfire question

65notch

New Member

Jun 18, 2005

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661 Cali

Oct 14, 2006

#1

• Oct 14, 2006

• #1

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

New Member

Jun 18, 2005

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661 Cali

Oct 14, 2006

#2

• Oct 14, 2006

• #2

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

 

Dothang67

New Member

May 9, 2006

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Oct 14, 2006

#3

• Oct 14, 2006

• #3

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.

 

H

headgrinder

Member

Apr 29, 2005

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san rafael ca.

Oct 14, 2006

#4

• Oct 14, 2006

• #4

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

 

K

krallman

New Member

Mar 3, 2006

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Hurricane, WV

Oct 15, 2006

#5

• Oct 15, 2006

• #5

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

Founding Member

Apr 12, 2002

6,698

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tucson,az

Oct 16, 2006

#6

• Oct 16, 2006

• #6

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

 

5

57fairlane

New Member

Apr 2, 2005

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Oakwood, GA

Oct 16, 2006

#7

• Oct 16, 2006

• #7

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

New Member

Jun 18, 2005

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661 Cali

Oct 16, 2006

#8

• Oct 16, 2006

• #8

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