Hi all,
I have a '70 Camaro with a '72 Chevelle 454 under the hood. The car has been sitting for 7 years. After replacing a few fuel lines that were dry rotted, she cranked up. The engine runs smooth with no skipping but at idle I'm getting backfiring from the exhaust. Even when it does backfire, the engine is running smooth as ever. Any suggestions are more than welcomed.......thanks in advance!!

 

Make sure you're hearing what you think you're hearing. Is it like a "putt-putt" out the tail pipe? That would more mean it's the valves. If you're actually hearing a "pop" or a "pow", that's unburnt fuel burning in the exhaust. In proper terms, a "backfire" comes out the intake, an "afterfire" is what comes out the exhaust. Exhaust doesn't backfire, but that's what people tend to call it. Since the car has been sitting for a number of years, you'd want to go over everything because there are a number of things that could be causing your issue, such as: poor fuel supply (the carb itself, bad fuel pump, clogged filter), the carb running rich/overflowing, exhaust valves not fully seating, ignition timing out of adjustment. After sitting so long, I'm surprised the engine is running as well as it is. Rebuild the carb (that's suspect #1), replace the fuel filter, replace the spark plugs, wires, cap and rotor, points & condenser too if you still have the old style ignition, and reset your timing. I wouldn't be surprised if your fire goes away after doing all that.

 

Greatly appreciated input.......thanks!

 

The carb was the culprit! Running fine now! Thanks for the help!