backfiring when engine cold - Team Camaro Tech
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post #1 of 5 (permalink) Old Jun 10th, 15, 03:47 PM Thread Starter
bob
 
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backfiring when engine cold

I have a 1969 camaro with a 427 motor, double pumper holley carb. When I first start and drive the car it backfires and feels like its running on 6 cylinders. What could cause this? Thanks for your help.
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post #2 of 5 (permalink) Old Jun 10th, 15, 06:02 PM
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Scott
 
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Re: backfiring when engine cold

Does it clear up after warming up? Choke?

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post #3 of 5 (permalink) Old Jun 10th, 15, 08:23 PM
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Re: backfiring when engine cold

And don't forget that there are two states of "backfire" one is pre ignition in the carburetor and this is caused by timing issues most of the time, and the other is post ignition where raw fuel is ignited in the exhaust system having not been ignited in the cylinder during the ignition sequence of the crank.

Pre-ignition through the carb often includes flame ups from the throat of the carb.

So where does yours backfire from?

Check you initial timing and choke idle speed and vacuum advance setting.


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post #4 of 5 (permalink) Old Jun 13th, 15, 03:46 PM
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Re: backfiring when engine cold

Backfiring = a lean condition. Adjust the choke.

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post #5 of 5 (permalink) Old Jun 13th, 15, 06:10 PM
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Re: backfiring when engine cold

Backfiring a lean condition? Always? Backfiring out the exhaust is usually caused by late timing.
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