I would strongly suggest that you learn how the advance system on a stovebolt engine works. The pinch clamp has exactly NOTHING to do with how the vacuum advance makes the housing move in the engine block. All it does is establish the initial position of the housing. Something is wrong that you haven't discovered yet.
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!