A quick swap in of a points distributor is a simple test. Then if it runs better without backfiring, he will know his problem is in the ignition system. Then he can repair or replace it as he sees fit.
Simple process of elimination, ultimately it's
@Jbarker that is going to find what the problem is. We are just trying to lead him to discover it by giving him a few options to try.
Yes, pictures of all of the spark plugs in order as they came out is a great idea. The pros on here can read how they are burning, and can relay the info of where any problems are.
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