[Bobcat]

About why engine builders don`t like vacuum advance .... I was told long ago that the "problem" was that when you went to WOT suddenly , the vacuum drop lagged behind enough to cause a momentary over advance condition ... while some others have said that was BS . I have no idea who`s right , however , I have a mechanical only advance on my MSD and would be interested in your results if you try a vacuum advance with Don`s bushings .
As a side note ... he told me you can "fine tune " the bushings by putting them in a vise and SLIGHTLY elongating them . This would allow more initial , but keep the max in the 36 degree range . Just make sure they slide freely in the slot . I was lucky ( I think ) as I hit what I was looking for without doing that .