Look to your distributer shaft and see if there is a lot of play side to side. If one was looking at the pattern on a scope there would be a dwell variation in a curve.

I have had loose distributers where the load of the ignition points when suitably openned drove the shaft so far to one side that the trigger points didn't open on the other side of the distributer. In such cases the optical trigger is the solution as without the one directional loading of the ignition points the loose shaft will trigger the bottom symetrically loaded points will work.

Just a thought.

No play in the distributor shaft. -Mike

It's free :) I would give it a try.

Stinger,
There is no felt pad under my rotor, if that matters. However, the only thing I think that could be wrong with the distributor is the lobes on the shaft that open and close the trigger points. They look OK to me, but since I do not have a new distributor to compare, I do not know for certain that the lobes are not worn down too much. -Mike

I see.

I would be inclined to take it to a High School or College and have then scope it for you.
I would let them learn while I get the print out. I would get 8-cylinder parade, group of 3, and individual cylinder shots in a clear EKG style printout.

I wish you luck and stay tough.