Limiting mechanical advance?
 

Is there a simple way to limit the amount of mechanical advance on a GM points style distributor?

Yes... either buy different weights with less advance (more material to limit the amount of swing) or build up small tack welds on the weights where they contact when open to limit the total amount of swing. Grind the tacks down until you achieve your desired mechanical advance. This is best done on a distributor machine.

I was afraid of that. I was hoping to do it without a distributor machine. I know that advance refers to crank degrees, does the distributor spin at crank speed or cam speed?