Aluminum Heads or Rebuilt Iron Heads 396 Big block

[nitrosport_5]

Ever since getting my 72 K20 together i have had random issues with intake valves sticking. The engine is a 396, GM forged crank, stock rods, Speed pro forged dome pistons, Comp XE268H hyd flat tappet cam, and 3856206 closed chamber heads. The first time the intake valve on #1 stuck was the first fire up after break in, the local machine shop said the tolerances were too tight and went through them again. After another 1500-2000 miles the same valve stuck again, and again the machine shop went through the heads. This last time i had 4-5000 miles on them and was thinking I was in the clear, but the 6 and 8 intake valves stuck this time taking out a lifter and for some reason the coolant pretty much completely drained into the oil.

So before i continue, i plan to find a new machine shop to look over the block and make sure there is no cracks causing the oil/coolant to mix but where i am torn is if i should have my stock heads checked and redone again if they are not cracked, this time by a different machine shop, or upgrade to aluminum aftermarket heads. im not looking to build a race car, I just want to make a decent amount of reliable horsepower without spending every dollar ive ever made.

If the aluminum heads are the way to go, or my heads are cracked and junk, can someone help recommend a good set of heads that will work with the parts ive already got? Ive been doing some digging and most of the heads that i come across are not setup for a closed chamber piston.

[68c10owner]

The issue you will find is that nobody makes a aluminum head with a small enough chamber for the closed chamber 396. Your only option is the Edelbrock TBI head but Im not sire the chamber will work with the pistons. They are the other head at 100cc`s.

You can rebuild your heads and they are fine for what you are doing. Does sound like you need a new shop

[Tom]

New shop with OE heads. The oval ports were good heads.

[Prong]

Edelbrock 60439 heads may work if you decide to go new. 100cc chambers should keep the compression up.

[dfarr67]

Check out Chad Speier maybe he has something.

[nitrosport_5]

Well my block ended up being cracked, so the 396 is no more. I picked up a 454 block with a set of 781 heads and am having them rebuilt. I think I will end up going with a stroker crank and making s 496 out of it. I've heard the 781 heads arent too bad.

[sweetk30]

049 or 781 best 2 off the shelf large oval port heads . lots say to up the valve size over stock and they will flow more . they can be made to make real good power over stock for a little work .