Hello all, I am having a problem with my 1972 Skylark with a 350 2bbl. When the engine is cold, it backfires (through the carb) every time I touch the gas. Sometimes, this stalls the engine, which irritates me at traffic lights with cars waiting behind me. Once it get moving and I am on the gas it is fine. If I let off of the gas, even while moving, it will backfire next time I press the accelerator. Once it warms up, the problem is gone. However, I work about 5 minutes from home, so I pretty much always have the problem. I understand that backfiring can have many causes, but can anyone make any suggestions on where I might start? When I search online, a lot of what I find is about backfiring through the exhaust (afterfiring). Thanks much.
Do you have the metal tube that goes from the exhaust manifold up to the air cleaner snorkel installed. It's designed to heat the air so the carb can run leaner during warm up without backfiring. Another big problem could be your choke, make sure it is closing properly when cold.
Make sure the choke is working properly. The backfire at throttle tip in could be caused by not any squirt on the accelerator pump. You may need a new one. Also if you have points in it double check the setting (dwell). This needs to be done first then make sure the timing is set correctly after the points are set. When the throttle opens up if there is not enough gas to cover up the hole you caused by opening the throttle the engine will backfire so check the pump to see if it is squirting gas if not replace it.
I think that is a great place for me to start. My car does not have this tube installed. I just picked up a new tube and clamps from the auto parts store. I will install them as soon as I get my car back from the shop(separate brake issue). Thanks much.
Backfiring through the carb means it is lean. Make sure there is no vacuum leak and that the accelerator pump in the carb is working correctly. The Pre heater hose is a good idea on a stock engine, and make sure your vacuum advance is hooked up and working correctly.
I have a 72 350/4. Now I'm getting a popping sound when cold and a very rough running engine. I was working on getting the secondaries to kick in and must have messed something up. I took the rod off. It didn't help the secondaries, so I put it back. It ran great cold, now it's a pig. Once warm....it runs great Any thoughts?
