I'm pretty sure the distributor hasn't been messed with other than high mileage. Oh, except the vacuum advance was replaced... possibly with a different washer pack, but it doesn't seem to be the problem, anyway. Just curious -- what is the effect of adding/subtracting washers to the vacuum advance? Does a thicker washer decrease the amount of advance, or the other way around? They don't discuss this in the FSM at all.
