backfire/afterburning

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Jul 10, 2005 | 08:01 PM

VETTE077

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From: JONESBOROUGH TN

backfire/afterburning

New plugs,carb adjusted,timing set by Lars instructions.Edelbrock carb,manifold,mild cam,headers and dual exhaust.Car runs great but backfires or afterburn through exhaust when letting off of throttle.

Last edited by VETTE077; Jul 10, 2005 at 08:06 PM.

Jul 10, 2005 | 08:23 PM

evil herbavore

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I've seen that happen with an exhaust leak.

Alternately, a smog pump system that doesn't have a good decel valve can do it too (injecting air into the exhaust during decel).

Jul 11, 2005 | 12:25 PM

VETTE077

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From: JONESBOROUGH TN

No air pump or any pollution devices on engine.No exhaust leaks.

Jul 11, 2005 | 02:11 PM

lars

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From: At my Bar drinking and wrenching in Lafayette Colorado

If you're getting afterfire (popping) through the exhaust, you're running lean. Richen it up.

Jul 11, 2005 | 03:35 PM

VETTE077

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From: JONESBOROUGH TN

Thanks Lars, I'll readjust carb

Jul 11, 2005 | 05:29 PM

lars

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From: At my Bar drinking and wrenching in Lafayette Colorado

VETTE -
You may need to do a metering rod or jet change to richen it up; richening just the mixture screw adjustment will probably not give you enough to solve the problem. Your headers and good exhaust are leaning you out across the metering range, so bump it up a few notches to compensate.

Jul 12, 2005 | 07:22 AM

VETTE077

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From: JONESBOROUGH TN

Thanks for the info Lars. I had it backwards I thought being to rich would let unburned fuel make it gargle and pop in exhaust when I let off.Also because of the smell of the fumes after I shut it off I thought it was rich. Thanks again.

Last edited by VETTE077; Jul 12, 2005 at 07:39 AM.

Jul 12, 2005 | 10:29 PM

DBM_NJ

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From: Ocean Gate, New Jersey

I purchased a '73 350/L82 last winter and it came with a very loud unidentifiable exhaust system that sounds great on acceleration - but pops like crazy when downshifting on a Parkway exit ramp. Where can I get metering rods to experiment with?