3993820 BBC heads

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12-11-2006, 07:18 PM
chevy427tall

3993820 BBC heads

found some heads for sale here in wisconsin, casting 3993820, (wants $250 for them) I read a few good things about these heads on different sites, just wanted to know if anyone has used these heads and how well they performed? i think there are like the 781 head but samller chamber, i had a set of 781 heads but one had a crack in it and i sold the other, still in the process of putting together a big block (427 tall deck block, .060 over, 4.500 stroke, going to be dumped in a truck)

thanks
12-12-2006, 08:45 AM
erik erikson

Quote:

Originally Posted by chevy427tall

found some heads for sale here in wisconsin, casting 3993820, (wants $250 for them) I read a few good things about these heads on different sites, just wanted to know if anyone has used these heads and how well they performed? i think there are like the 781 head but samller chamber, i had a set of 781 heads but one had a crack in it and i sold the other, still in the process of putting together a big block (427 tall deck block, .060 over, 4.500 stroke, going to be dumped in a truck)

thanks

I can tell you they have a 113 cc combustion chamber and they flow approx. 280 on the intake side and 190 on the exhaust side at 28 inches of water and at .500 lift.
I.M.O. these heads are to small if you are looking for much over 450 hp out of your engine but you will make great torque at lower rpm's.
12-12-2006, 10:23 PM
vortec king

I had a set of 820's before that went on a 427, and i flowed them out with stock size valves and three angle. they flowed 269CFMin and 187 CFM ex with a little pocket porting, i doubt they flow 280, because the intake valve is just to small, but cut them out for big valves and 280cfm could be possible. there are nice set of heads! that 427 was MEAN!
12-13-2006, 03:06 AM
erik erikson

Quote:

Originally Posted by vortec king

I had a set of 820's before that went on a 427, and i flowed them out with stock size valves and three angle. they flowed 269CFMin and 187 CFM ex with a little pocket porting, i doubt they flow 280, because the intake valve is just to small, but cut them out for big valves and 280cfm could be possible. there are nice set of heads! that 427 was MEAN!

I guess I should have been more clear in my post.
The flow numbers I posted where for a 2.19/1.88 valve with under cut stems, bowl blend,gasket match and some combustion chamber work that I did.
Either way the heads are to small for a BBC swinging a 4.5 in stroke.