Check the top distributor shaft bushing for wear. if you can push the cam side to side and change the point gap, replace the distributor. Every 1 degree change in point dwell from a gap change causes a 2 degree difference in spark timing at the crankshaft.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!