Dave, I don't know if I'll be much help, I've never built a Buick so I don't know what they like. I'm a little surprised that you're using 10.5 pistons with iron heads on pump gas. Are you sure that's gonna work o.k.? Like I said, I don't know anything about the knock characteristics of Buick heads/pistons. You know, in '64 we had good gas.