I can find no info on cc's either but I would guess that they are 75
or 76 cc's because all the heads in the 39989xx range are that size.
(most are 76 cc's) One source shows them for a 72 to 73 350's and
another one shows them as 72 to 75 350's and a third source shows them
as 72 to 74 so take your pick.
I come up with 9.8 to one on a 350 and a flat top piston with no
valve reliefs and 9.2 to one for a 327 with 76 cc heads. (all these
assume a .030 thick head gasket and bored .060 over) If there is valve
reliefs figure on .25 to .5 less depending on size of reliefs. A stock
bored 327 would be just a bit under 9 to 1. so the overbore is good
for about a .25 increase in compression. ALso if Head gasket is
thicker CR would be lower and if gacket is thinner CR would be higher
as it also would be if heads have been milled a bit to true them up.
new valve seals...valves.. but other than that.. stock. I only like the
heads because they are a non prone crack head and I don't intend (now that I
seen the 060 piston) to turbo it.. That is being done to the 283 Thanx for
all the help... I was stumped that no cc was givin to those heads.. but I
guess. everyone knew in the ealry seventies.. 76cc was the norm.. I wasn't
an itch when these heads were made.. lol
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