Head CC ?
 

In a conversation with a friend, he mentioned his late 70's 350 stocker is allowed to have a 624 head, milled to 63.3 cc. I questioned how it is that the spec is so small for a head always known as a 76cc smog head? So I got looking around, the same exact head is only allowed to be 73.7 cc on an 86 truck 350, which is far more realistic. GM only made the one 462624 casting (excluding the newer hecho en mexico) So does anyone know why such a large difference?

Re: Head CC ?
 

882's on 350's on 73,74,75 nova's are changed to 64ish cc from 76,my brother has one been sitting for 7-8 years now, but when we did it we had to angle mill .160 on his heads.
I don't know why it is changed that much we called and double checked that it was'nt a misprint .
Mike Taylor 3601

Re: Head CC ?
 

I think that you'll find that the "misprint" came about in around 1971!

Re: Head CC ?
 

I remember the spec sheet we had back then around 95-96 showed head cc revised to 64ish I think it was 63.3 and we put on 64 had revision date for the spec but can't remember date.
Or did you mean they changed the spec starting with 71 cars Billy?Which would sound right because 70 probaly had 64cc heads
Mike Taylor 3601

Re: Head CC ?
 

There are numerous examples of "smaller than real life" combustion chamber cc's published in the NHRA Engine blueprint specs. Maybe these will be corrected one day...

Re: Head CC ?
 

Does anyone remember the 215 casting bbc head being 116cc in the early 90's? My dad swears thats what his had to be, but for a while now they claim 96, like the bathtub chamber heads should be.

Re: Head CC ?
 

I have a tech sheet from 1983 that shows the BBC 215 head listed as a replacement for a 1967 396-325 and a 96 cc spec. When you have replacement heads assigned to an engine, the original specs for the engine as received from the mfr is generally what is the rule, not the characteristics of the head itself. Mid-60s 327 Chevs use the "double hump" series of heads - 461, 462, 291, 186, 041 - yet use a 57.5 cc spec. We all refer to those heads as "64 cc" heads and rightfully so because that is the manufactured characteristic. What you really need to question is the specs in the book and the source; some did not come from the mfr.