['ol Pinion head]

Originally Posted by steve25

Unfortunately the head flow capability that the Olds heads had be it 425 or 455 cid sucked when compared to even a stock D port high comp head of the era, no less the RA4 heads!

Interesting that you've bench flowed Olds stock B, C, D, & F heads & they flowed less than a '67-70 big valve Dport head's 205-208 cfm. the peak flow data I've consistently seen on many untouched Olds heads with good valve guides is they flowed between 230-240 cfm at .500 lift (28" depression). No port work. From flow sheets all performed the same day on my own round ports that's in the range of the best stock flow '71 HO's to stock 722's.