Thread: engine backfire out exhaust

Tweet

ok so i finally got around to geting my new intake put on. i have put a new carb on top of that too. Its a chev 350 with a edelbrock performer EPS intake and a holley 570cfm street avenger carb. when i went to flash it up it started but had a popping out of the exhaust. it runs fine but it has a loud pop every 2-3 sec. what could cause this?

check your timing.

It does it in every position i put the distributor in. I thought my plugs were fouled so in went new ones. still same thing. seems to run alright but a loud pop ot of the tail pipe. i dont want to let it run like that in fear of damaging somthing. So i set it at top dead center again same thing. cant figure it out.

Mixed up plug wires, bad wire, bad plug??? All possible causes.

possibly vacuum leak, or leak at headers, sucking air in also.... sometimes a small leak in the exhaust system will suck air in and cause what sounds like a small backfire

Are you running lean?

-Chris

If you're 100% sure you've got the drive gear on the distributor lined up right, start checking the carb. Since you stated that it happens every 2-3 seconds, that indicates that fuel is pooling in the exhaust and lighting off.

Pull the plugs and check the color of the tips. They should be brownish to reddish-brown. If the plug is wet or really dark, you're running rich.

What is your fuel pressure? The Street Avenger uses 5-7psi.

Also, you didn't say if this happens at just idle or under acceleration or under cruise or all the time.

Is the distributor vacuum advanced? If so, make sure you've got it connected to the right port on the carb. The Street Avenger has 4 ports and each one is specific for each application. The port for vacuum advance is just to the right of the electric choke, just above the idle mixture screw.

Start with that and get back to us letting us know what you've found.