6. If you can’t visually determine which advance slot is shortest, the inside jaws of a dial caliper makes it easy. The length of the advance slot in this particular points cam assembly measures 0.450 inch. When considering that each 0.0125 inch represents one distributor degree of spark lead (two at the crankshaft) and the bare advance post measures 0.190 inch, the advance slot can provide more than 40 crankshaft degrees of centrifugal advance. That’s simply way too much for reliable operation from most any Pontiac V-8.