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Backfiring through carb, please help

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Old 06-18-2005, 11:53 AM
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Car: 1991 camaro RS
Engine: 305 Carb
Transmission: 700R4
Backfiring through carb, please help

I just completed my TBi to carb swap, and i got her up and running. When i have the timing set at 0 it pops through the carb when i rev it up. But when i advance it to about 8 degrees it stops doing it. That is running about 3 PSI and ive tried other psi also but it does the same thing. What could cause this? Am i just gonna have to leave it at 8 degrees?
Old 06-18-2005, 12:07 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
8 degrees initial timing, set with the vacuum advance disconnected, is a good starting point. 8-12 degrees is typical.

Fuel pressure does not affect carb performance (until there is too little to keep the bowl full or too much for the needle & seat to shut off).
Old 06-18-2005, 12:30 PM
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Car: 1991 camaro RS
Engine: 305 Carb
Transmission: 700R4
8 degrees initial timing, set with the vacuum advance disconnected, is a good starting point. 8-12 degrees is typical.
Ok, i just found out that i had to dissconnect the vacuum advance. I have been setting the timing with it hooked up, so ill will set it again. Also i am gonna adjust the carb, could this also cause backfireing?
Old 06-18-2005, 12:38 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Adjusting the idle mixture screws probably won't have any effect on that.
Old 06-18-2005, 01:38 PM
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Car: 1991 camaro RS
Engine: 305 Carb
Transmission: 700R4
Well, i just got done messing with it again. I had the timing at 8 degrees and still backfired, this time it shot a big flame and kill the engine. It seems like it only does it with the car at a idle, then mash the gas all at once, and it happens. Should i just try to advance it some more?
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