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massive amounts of backfire

Old 09-03-06, 07:47 PM
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massive amounts of backfire

so my 79 starts and idles good but ANYTIME you hit the gas it backfires. even in neutral i cant get it to rev past 4000 and when driving 3000. if you get on the gas hard it totally dies and backfires and stalls. im not really sure what to do about this...

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Old 09-03-06, 07:51 PM
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ur probably running very very rich, i dunno.
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Old 09-03-06, 09:18 PM
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Check the dashpot...once I adjusted mine (after rebuilding the carb) it significantly reduced (but didn't eliminate) the backfiring. Now it just backfires when I really get on it hard.

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Old 09-04-06, 01:44 AM
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Check timing and points..
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Old 09-04-06, 08:22 PM
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Check your exhaust for small leaks
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Old 09-05-06, 12:41 PM
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Actually, running very lean will cause backfires, not very rich. It is called a lean misfire. On my FB there was a large rubber vacuum hose that was resting on the header and burned a whole in it, causing large vacuum leak and thereby massive backfireing. I used a can of brake clean to spray around the carb and all the vacuum lines as it was idleing. When the engine smoothed out, I checked the area I had sprayed and found my vacuum leak.

Also check your fuel filter. If you are getting good fuel and have no leaks, I would look at the ignitors/points to see if they are going bad.

Usually if it runs worse at idle, and smooths out as rpm increases, fuel/intake system is at fault,
If runs smoother at idle and gets worse as rpm increases, ignition is at fault. Make sure you check cap wires rotor, etc.


ON EDIT: Sorry, just read that you said is a 79, so no ignitors. Make sure your points aren't burned and the gap is correct.

Last edited by SSRx7; 09-05-06 at 12:43 PM.
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