grounding distributor

[barkleydave]

All good areas to check. Question: are you using float-a motor mounts? If so do you have a ground strap from your battery to the transmission to insure a solid engine ground?

 

[katy]

You could try a temporary ground wire from the screw that holds the condensor in to the body or frame somewhere.

 

[Mike Peters]

Some years ago the distributor cap body (where the brass spark plug connectors attach) shorted out internally on my AA truck. This caused cross firing between various cylinders, resulting in much back firing. Sounds a bit like your symptoms, although your back firing is intermittent. I put a different distributor body on the truck and it ran fine. If you have another distributor body, try it on your car and see what happens.