I have a set of casting #3909802 heads. What is the orig valve configuration and what might be the best way to spruce them up?

according to www.mortec.com (http://www.mortec.com) those heads are 1967 closed chamber large ovals, they have a 101cc combustion chambers and 2.06/1.72 valves stock.
they are good heads, and since they are closed chambers they will make more compression over open chambers given the same piston dome size.

what to do with them depends on what you want out of the car and what shape the heads are in. the heads will perform great stock, but depending on how aggressive you want to get you may want to have them pocket ported, have the chambers unshrouded and have large valves installed(2.19/1.88) on top of a complete rebuild.

what are your goals/plans for the car? tell us a little more about car/combo as well, im assuming its a 396??

Thanks rat - I am planning on a stealth intake,holley3310,1"7/8 headers,turbo350,3.55posi.
the cam?? Either a voodoo 262 or 268 or the UD280/288. I have not decided which one? Any input?

sounds like you want a good performer but nothing wild, i would stay with the stock valves and have the heads rebuilt.

all of the cams you listed sound like a good match depending what compression ratio you end up with, its hard to make a reccomendation without knowing the comp or your planned redline.

guessing i would say with 9:1 to 9.5:1 i would go with the voodoo 268, but would probably step up to the 280/288 with anything close to or at 10:1.

only thing i would change is the headers. personally i would go with the 1 3/4 headers, but if you already have the 1 7/8s dont worry about it.

Rat can my cr be estimated if I know on the rebuild stock replacement pistons were used, block 30over,and 10 off the heads just for clean up/ How did you know the valve size? I went to mortec site and saw the 101cc size but no mention of the valves? Thanks

your comp can be estimated, but i have to know either the piston part number or dome volume of the piston in ccs and compression height of the piston.

on the valves, oval port heads only came with the 2.06/1.72 valves. the ONLY heads that left the factory with the larger valves were the rectangle port heads.

The engine kit I used some 20 years ago from trw included what they called factory replacement pistons! Oh well. Hey Rat - I read on another post that the bathtub heads had trouble handling any duration and had detonation problems? Can you explain what they may have meant. Are these good heads?

I'm no engineer, but from my firsthand experience, I've found if you hold a tight quench, the closed chamber heads are very good regarding detonation.

Can someone explain why?

they are good heads, people have run 10s with closed chamber heads and our own Chris aka MR 4speed uses them on his 454 in a 70 chevelle. hes running 10.25:1 comp, a 280/288 ud cam, 3310 holley, performer rpm, th400 with 2400 stall, 1 3/4 headers and duals(not sure what size). currently the car has 3.31s, but it had 2.56s and ran 12.99 in the quarter! it runs on premium fuel and he drives it to the track which is over 100 miles from him!!!

the detonation problems associated with the closed chamber heads werent from the chamber design. it was the fact that the comp ratios in the earlier engines were higher with the same cam, this wasnt a problem until the lower grades of fuels were introduced after these engines were built. this is exactly the reason the comp was lowered in the later engines, crappy fuel.

no matter what chamber type is used it all boils down to the compression ratio and what camshaft was used. too little a cam for the compression and it will detonate.

I see, Thanks again RAT!!! graemlins/thumbsup.gif

I believe unshrouding the valves begins to make the heads open chambered! That was the real benefit HP wise in the open chambered heads. GM did it for emissions reasons.
You can't get too carried away with the unshrouding btw, there is water close.
Ron

i just wanted to mention you really need to find out what pistons are in this engine.

the piston domes are shaped differently to accomodate the different combustion chambers between open and closed chamber heads.

open chamber pistons are a no no with closed chamber heads, but usually closed chamber pistons will work with open chamber heads. there are some exceptions which i wont get into, but this is the general rule. flat top or d-cup pistons will work with either head since they have no dome.

i dont know what state your bbc is in, but you really should look the pistons over to try and find a part number on them. this could save you some headaches down the road.

take care and good luck
Brandon

They are supposed to be stock replacement. I know they are raised in the bathtub area to match the heads. Yhats all I know. Thanks for the input!

By the way, most folks use the last 3 digits of the casting number, not the first, so yours would be 802's. Just FYI