The first couple years, they used .060. After that they changed to .045. Why? Who knows? In the early HEI days the rotor had a bad habit of burning a hole in it and shorting to ground. When they switched to the white rotor instead of the black, that cured the problem. I think they closed up the gap because of too much resistance, making the fire burn thru the rotor.Most Oldsmobiles used .080, so either will work. Joe
