OK, I have the stock heads on my 1967 SS 396 which I believe are cast # 3917215. They are oval ports and I think the inatkes are 2.06 and exhaust are 1.72,They are 100.9cc. Now how much of a difference can I expect from a 1965 Head from a 396 with the following modifications. The valves are enlarged to 2.19/1.88, They have been bowl Blended to 115cc, They have been gasket matched on both exhaust and intake and I think there might even be some Polish and porting done to them. I know I'll lose some compression going from a 100.9 cc to a 115cc ( I have stock compression 10 1/4) But will I pick up power with the other things done to them?

Originally posted by SSpete67:
Now how much of a difference can I expect from a 1965 Head from a 396 with the following modifications. The valves are enlarged to 2.19/1.88, They have been bowl Blended to 115ccSounds like someone was trying to make an open chamber head out of a closed chamber head. :confused:

I figure the old -206 head was about 96.7 to 97 cc's before somebody unshrouded the heck out of the new bigger valve addition job.

I do figure it would be fine if you could keep your CR. close to the same but that probably will entail new pistons so may not be practical??

pdq67

PS., I'm kinda supprised they didn't hit water by the sparkplug side quench lay-back if they laid it back???

Get your 215s done. I don't think you can open an early head to anywhere near 115cc without hitting water. When you do yours you will know exactly what you have.