RRJD, My 915 post was stated that way because there were 915 heads that came with a smaller exhaust valve than the HP 915 heads and all later bigblock Mopar heads. You could look it up.
R.

67 piston CH is about 2.000". Typically .080" or so in the hole. Perfectly flat.

this is a question. haven driven different cars do you think the closed chamber heads including 383 413 426 440 cars have a little more go, esp. lowend than the open chamber head models?

I have indeed driven and been in a lot of hp cars, and spent a lot of time with them at the track as well. This is what I can say with confidence, my butt meter is worthless. How the performance feels, and reality can be very different, in either direction.

it just seemed to me the 383 closedchamber head motors pulled a little better stock. now thats with your basic bolt ons alu intake 750 carb/ headers.i cant say much for the 440 a havent put my 915 head 440 in my truck yet but its a basic stock rebuild.trw 2266 pistons small summit cam.

IMO, there is no performance difference between the 906 and 915 heads given equal compression and valve size. The 906 heads untouched may even flow better than the 915's. The 915's on a 68 and up motor are just an easy way to get you more compression...8 and more chance if pre-ignition with pump gas. Now if you put the 906 heads on a 67 motor, it will be a low compression slug! The 906 heads are good flowing heads and can be made to flow even better with a little massaging. High compression on anything but full race is not all that great.