Reply to "Head selection"

[Jack! I would beg to differ. If the roller rockers lower the friction across the valve stem and at the fulcrum, and take less Horsepower to run; does this not "Free-Up" a few extra Horsepower?? Regards, Marlin.]

Yes, probably, but for power increases of 1% or less on a 300-horse engine, you'll never see such an increase on the street. As I said, even racers add roller rockers simply for the better efficiency, the reduction of valve-guide wear and the cooling effect on the oil supply.