From a prior thread the combustion chamber was said to be 68cc vs the stated 64 on #5 heads according to norm. I believe I have read the same info in a technical publication as well, and was surprised to see it in wiki. I have not confirmed this myself and the thread went off on a machining tangent, but thought this worth note to the powers that be.

 

Just a contribution here.
My G heads cc'd at 79
and the Ga's were 80cc

 

But do you know for a fact that they were virgin?

 

68CC!

 

I'm afraid not.
I was born in 82'

I bought the car in 1999 and it had the stock steel shim head gaskets.

 

There is no reason to believe these numbers are not accurate.

Norm

 

The #6s that came off my original motor were 69ccs. The #7s were 70ccs. I'm sure they were virgins also.

 

measuring the head thickness will tell you if they have been cut. dont forget these are castings&the cc's can be quite different from one same head to another ,,in fact even the same head can be different by a cc or more form the chamber at one end to the chamber at the opposite end.

i just cut some 307 5A's that were way differennt..one head needed .018 more cut than the other to get the same cc'c