65-85 under.

[Billy Nees]

Originally Posted by 442OLDS

Unless it's a misprint,the B of the B-O-P racers have 10.5 compression pistons in 1971,1972,1973 on the engine blueprint specs.

I always thought the 1971 engines started the era of low compression pistons and unleaded fuel.But I might be wrong,as I was only 5 or 6 years old at the time.I know the O got low compression pistons.

Wellllllllllllllllll, the B Racers DO have some friends in high places! AND some (most) of the "legal replacement" pistons DO have very advantageous piston dish volumes.