In Reply to: Back Fire posted by Paul in Mn on November 19, 2017 at 03:29:37:
Doesn't matter what voltage or where the distributor is located. Two possible causes for a back fire. One, slightly off timing won't do it all the time. Big mistiming will cause it to back fire. Second reason, Sticky valve or one that does not close properly will do it all the time. Build up of raw fuel in the chamber will explode during the exhaust sequence.
I had a Model A that back fired all the time. Changed the distributor, timed it many times all to no avail. Pulled the head, and sure enough one or two valves were sticking or not closing properly. As a precautionary measure, I replaced the valves and guides, ground in the valves and never again did it back fire.
My humble opinion.