Thread: Back Fire THru Carburetor Problem

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The back fire problem turned out to be sticky valves on new heads. Running the engine helped the valves loosen up and made the problem stop.

Did ya tune the holley? Mabey the power valve is shot.

Timing off or a vacumn leak? Just guessin'

I'd say advanced timing or not enough fuel. Why run only 3600 rpm? Back to your question, I just got done getting an engine running that was backfiring through the carb. Poured some gas down there to keep it running (not such a good idea but you gotta do what you gotta do) and eventually whatever was preventing it from getting fuel cleared out and it ran fine afterwards. I think the jets were gummed up, there was condensation in the float bowl, or the engine had carboned up and was preigniting.

Is this a brand New engine? If so Did who ever built the engine dial in the cam with a degree/timming wheel. Cam could be off.
Or the distributor could be to far advanced.Did you just put on the spark plug wires and if so are you sure that they are right.

~ Vegas ~

My thoughts:

1. Timing is off

2. You may have an intake valve adjusted too tight that once the oil pressure spiked up (cold thick oil on a fresh start), it is allowing the compression to come back the wrong direction.

3. You may have two plug wires criss crossed.

Need more details...like does it pop back when you are just spinning it over, or does it do it after 10 seconds, 30 seconds, or five or ten minutes???? What engine temp...etc.

Once you find your problem, repace the power valve in the carb. Backfires usually trash them. Not much more to mention, the others posting have put up the obvious problems. By the way, why only 3600 RPM??? Was that a typo???