I mentioned on another thread that I had some flow numbers for some 074 and 781 BBC heads and some people wanted to see them, so here they are.

The 074s were blended in the pockets and the short side radius rounded, but very little, there was not really much to grind. ports were pretty good as is.

The 781s are fitted with 2.19/1.88 valves. Pockets were opened and blended from the seats down the walls to the guides and short side radius rounded and everything in the bowl area smoothed and blended. Guide bosses left stock. Very simple basic pocket port job and took about 2 hours. Finished with three angle seats and back cut valves. Intake and exhaust runners got nothing but the casting flash ground off.

........074.........781

.100...64.4..........64.9
.200...145.2........141.8
.300...219.1........211
.400...261.6........265.7
.500...280.1........284.2
.600...295.3........289.1
.700...308.5........288.7

Heads were flowed on the same day, same machine.

I'm surprised the low lift numbers are as good as they are with these old big port heads. They have, actually, been a pleasant surprise on my street car. ( except for being as fragile as heck).
Did you check the exhaust side? I've heard thats where the "round port" 074s like mine really stink.

kamero68,

Do you know what bore size was used to flow test those heads?

My sons 781s flowed a little over 300 CFM on the intake with 2.19 int. and 1.88 exh. and seemed to run pretty good.

I did not get the exhaust numbers, I had carried my heads over with some customers heads, and when my driver picked them up he had not had time to finish mine yet. I never got around to taking them back.

4.250 test bore