Carb Backfires

[paperpusher]

Hi All,

I have a 65 Chevy 230 6 cylinder. The 2 barrel carb backfires or its more like pops through the carb. In most cases its while I'm trying to take off or under a load. But some times it does do it when I race the engine. Anyone have ideas of what could cause this please.

Thank You

[zippy]

Greetings, Paperpusher, and welcome aboard,

With back firing, the first thing I think of is bad timing. With computer controlled engines, we forget that the old ones are more complicated to set-up. You need to check your timing several ways: the basic timing with the vacuum advance hose plugged and then with the vacuum advance functioning. Your manual will give you the proper advance settings under several circumstances, you need to verify correct timing for each condition. You'll need a timing light and a dwell/tach.
If your ignition uses breaker points, then you need to make sure the dwell angle is properly set, too. I'm not that familiar with 6's, but back in the 70's I did quite a few SBC and BBC conversions to breaker-less ignition. It was well worth the minimal cost and effort to be rid of those pesky points.

Good luck.

[paperpusher]

Thanks Zippy,

I intend to check the timing this week end. While it was running I removed the vacuum line from the carb, the engine did not change at all.

Thank You