I got exactly 318 out of my old open chamber head with a 2.08 valve and have gone so far a best of 6.06 at almost 112mph@2880 pounds. The heads are tubed and I had to take everything available to hit that number. (Stock located pushrod). They are approximately 185cc runner and the short turn is not taped like some insist on doing. Lots of time and labor to get there.
