Quote Originally Posted by vortec king
I had a set of 820's before that went on a 427, and i flowed them out with stock size valves and three angle. they flowed 269CFMin and 187 CFM ex with a little pocket porting, i doubt they flow 280, because the intake valve is just to small, but cut them out for big valves and 280cfm could be possible. there are nice set of heads! that 427 was MEAN!
I guess I should have been more clear in my post.
The flow numbers I posted where for a 2.19/1.88 valve with under cut stems, bowl blend,gasket match and some combustion chamber work that I did.
Either way the heads are to small for a BBC swinging a 4.5 in stroke.