[sho305]

It works like a CDI. Its function is to retard the timing at low rpm. It starts at 0 advance and above 1K rpm it raises up to max of ~30 degrees at 2500rpm. Possibly what some of the big block people would love to have. The pickup is mounted advanced, and at under 2500 it retards the timing. There is a graph showing it in my manual. Sometimes mine kicks back when starting hot, makes me think mine is getting bad and not retarding it but hard to tell without checking the timing.