336 casting heads
 

So I finally got my heads inside and cleaned up enough to read the casting number on them, and they are 336. Now I pulled these off of my chevy 400. I did a bit of digging and the 336, as far as I can tell, never came on a 400. Are these heads any good ? If I were to get better springs, valves, and a valve job, what kind of power can they support. These are 76cc heads from everything I can find, so I will definitely be going with flat, if not domed, pistons.

Let me know if any of you have experience with this casting.

Thanks

- Brad

336 heads are one of the better of the "crappy smog 70's era heads". As they sit now they won't make much power.
They don;t flow that good stock.
But.... If you're wiling to invest some sweat into them you can change that and make them into a fairly good performance head. Good enough for 12's
If you were to fully port them (not just a pocket port job but a serious effort) and install new 2.02x 1.60 valves, a 3 angle valve job, drill and pin the studs, drill steam holes (400ci block) in the decks and maybe get them shaved some they will make well over 400hp with a good bit of camshaft. You can flat mill them to 68cc (about .060")

With a typical flattop and no block decking, shave them to 73cc for 10:1 cr.
If you 0 deck the block so the flat top pistons come right to the top @TDC, don't shave them at all.
If you're looking to mak more than say 425hp, sell them off and get some 72cc Dart Pro 1's (215cc ports) and play with them.

Music to my ears. I had misread the casting numbers some time ago and thought I had 882s, and from everything I read, there was no way they were staying, but given your input, I think I can do my buildup with these and then get aftermarkets on down the road. Again, Thanks a ton for the info.