A worn distributor shaft bushing will do this.It closes the point gap when it wobbles.It is very easy to check.Hook a dwell meter up and you shouldn't have more then 4 degrees dwell variation between idle and say 1500 RPM.Also you can rebuild the dissy with a new GM housing for a taxi(if it is still available from GM)This has two bushings that last forever.Hope this helps.
Wanted Good Woman:
Must be able to cook , clean , sew , tune engines and polish trucks. Must have old Stovebolt and garage. Please send picture of old Stovebolt and garage.
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