Hello everyone! I need a little help again please. About 50% of the time, after driving for a while, when I cut the car off, I'll hear a loud backfire after about 2 seconds after the motor dies down. I don't know what could be causing it or how to stop it. I doubt the neighbors like it much. The car is a stock 12A with RB Holley carb, headers, silencer, and muffler. No cat at all. Is there anything I should look at?

 

Mine does the same thing.

I like it.

 

Don't rev before shutting off the motor, let it idle for a bit, then shut down. If that doesn't help, the carb may be set too rich or in need of cleaning/rebuilding. Check timing too.

 

What do the plugs look like? Gas mileage?

You probably have fuel puddle's in your silencer. And your timing is high enough to ignite it. Lower timing a little (at least check it) Get a WB02 or go to a performance shop with a dyno and a WB02. Bring some carb jets with you and play fuel ressure to get your mixture right.

Or remove or move your silencer farther from the header.

Also air leaks in the exhaust can cause this. Check for exhaust leaks around the header flange esp.

Good luck

 

Mine does a quiet little "puff" after I shut it down, but once in a while it will give off a bang. It's done this ever since I installed the RB exhaust, even when I was using the stock Nikki. If your's is banging then look for air leaks as suggested above...

 

99% of the time that i've encountered backfiring its because of exhaust leaks.