Every time I get a "strange" problem, I post it here to get feedback before I venture too far in my efforts to correct the problem. This time my local, friendly mechanic was wrong about the vacuum advance allowing fumes in the dizzy cap.
I did not think it was possible, but he had not taken a good look at the set up and was speculating. The problem was mechanical - worn out dizzy bumping the cap off. I put in a "junkyard" unit and am back on the road. Thanks for the input and "steering" me in the right direction. This is a good forum! BW