At 800 RPM, you're starting to get centrifugal advance, which will make it appear you're over-advanced. Drop the idle speed to 500 or less, and use the screw clamp around the distributor housing to set the initial timing with the hold-down bolt centered in the slot. Then tweak the setting up or down a little if necessary for fine-tuning.
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!