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Author Topic:   popping and backfiring when letting off the gas
dode
Dirt Forum Champ
Total posts: 613
posted July 19, 2005 09:24 AM  
Popping through the exaust and carb. or just popping through the exhaust?My friends car pops through exhaust on corner entry and mine will once in a while when I get good speed out of the previous turn.And we run Holleys.KP can probably explain it be it good,bad or indifferent.I know this dont help much but I make faster lap times if i get mine to pop back at me.

sc1 racing
Dirt Freak

Total posts: 419
posted July 19, 2005 10:35 AM  
ive always been told if the car pops when you get of the gas the the carb is to lean. i bumped mine up to a 80 from a 78, and ran it, and it doesnt pop anymore, dang car runs awesome and yall would chit if you knew what i had in the engine...

dode
Dirt Forum Champ
Total posts: 613
posted July 19, 2005 11:29 AM  
It is my understanding that it is unburnt gas igniting from the heat when it hits the air (if you will). Are you running short exhaust? If you are running a longer exhaust system you may have an exhaust leak. I run an owm when I use shorty headers I get the popping. When I use long headers the popping goes away.

leapinlizard
Dirt Freak

Total posts: 402
posted July 19, 2005 01:09 PM  
High amount's of vacuum existing in the intake can pull fuel from the transfer slot under the throttle blades. Very little air is brought with it, so little that combustion can't occur inside the cylinder and unburnt fuel resides in the exhaust pipes from wide open application. A crack or leaking header gasket introduces air in to the super heated exhaust supporting combustion. A flame appears. Sometimes it's a carb problem indicator and sometimes it's a idle circiut fault. But mostly it's a cam and carb combonation(overlap vs idle trim)that does it.



Flanndad
Dirt Freak

Total posts: 255
posted July 20, 2005 05:11 AM  
Mine popped out of the exhaust also, I could not keep one of those standard donut gaskets to stay in tact.
Installed a steel donut gasket and my popping went away.

dode
Dirt Forum Champ
Total posts: 613
posted July 20, 2005 06:40 AM  
Did you go to Linn County, Saturday?

Flanndad
Dirt Freak

Total posts: 255
posted July 20, 2005 06:55 AM  
Replace it with the steel donut gaskets, those fiber ones don't hold up as well.

dode
Dirt Forum Champ
Total posts: 613
posted July 20, 2005 07:18 AM  
I bought mine off the pit parts man.
I never bought it anywhere else, but I would think an exhaust shop should be able to get them.

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