Great link maxwell417. I read about these some years ago and would like (might, even) to build one for our two 2.6 Troops. So much exact precision as well as durability required to prevent toasting engine internals. Lots O' racers use slotted sprockets on a 3 bolt adapter, but I've always thought the centrifugal advance would cover a wider range of driving conditions. Again, great link...Thanks!