Warm backfire

[William F.]

On a warm, but not any length of heatsoak, restart my '62 340 hp with AFB carb will "pop"-backfire after turning over a little longer than expected and then start and run fine. I'm probably holding accelerator part way down, not pumping. I'm running 10, maybe 12*-I'll recheck initial advance . I know the centrifugal only distributor is set up to give 26* total, starting to come in at 900 rpm which would already give 36-38* total advance when it's all in. A Corvette knowledgeable friend suggested giving a little more initial advance and see if this cures problem.Would more advance be too much? What do some of you think is causing the backfire and would would you try to correct the problem?-don't want a fire.
Thanks in advance

[Edward J.]

Re: Warm backfire

Bill, You may be experiencing gas percolation after shut down which is a common problem these days with ethanol fuels. I have a similar problem with my 63 SHP on those warm summer days. My car runs perfect on cooler days and no re-start problems. If your car runs the same when cold, its likely the issue. I also rebuilt my Carb. and set the floats about 2/32th lower that the spec.s called for, because the fuel was dripping down the throat of carb. after shut down on the hot 90 degree+ days.

[Timothy B.]

Re: Warm backfire

William,

If you know the engine is in good tune, verify the TDC is correct on the engine marks so you know the timing is correct.

[William F.]

Re: Warm backfire

I'm using non ethanol 93 octane gas. What's easiest way to verify TDC on #1? Do I have to use a piston stop?

[Timothy B.]

Re: Warm backfire

William, Piston stop and turn the engine by hand.