Find someone who smokes (yeah, that's a major project, I know!) and have him/her blow a little smoke into the tube attached to the vacuum advance. Any smoke at all out of the housing is too much! replace the advance if there's any leakage at all.
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!