Hi There!

Here's the deal, I've bought a pair of cylinder heads, cast iron, casting #083 64cc (same as #217), to go on my 1990 IROC-Z. They are the "valve cover center bolts" type, just like the originals.

I know they were used by GM Performance Parts, to put on 285/300 hp crate engines.

I've also bougt a ZZ4 Camshaft... My goal is to have about 350 hp.

The block itself is a 350 casting 638, 4 bolts mains, it as been bored ".030 over and balanced. As for the fuel injection, I'm using a ported TPI plenum, stock runners and intake manifold. I have 24 lbs fuel injectors from a '99 Z28, an adjustable fuel pressure regulator, MSD ignition 6AL, SLP 1 3/4 headers, MSD coil.

Here's the question... Does the heads have to be ported to obtain my goal?? How much hp can I expect from them being stock??

Any pointers or ideas here would be GREATLY Appreciated!!!!!

Thanks a lot guys!

A guy who really needs help!

 

How to Build and Modify
Chevrolet Small Block V-8
Cylinder Heads

David Vizard
ISBN 0-87938-547-2

 

Yeah, get that book...it will pretty much answer your questions.

In the short term though, I think it would depend on your cam choice. With enough duration, you could get your goal, but it would kill low end response.

I would look around for similar flow #'s for these heads, if you can find them, and go from there.

Good luck

 

Yes you'll need to port those heads to reach your goals with a TPI
system. But you can do it at home and keep the stock 1.94 /1.50 valves. Concentrate on the first and last 1.5 inches of each port.
enlarge and square up the port opening to match the intake manifold and blend back in 1.5". Exessive enlarging is not nessessary. On the bowl side remove and blend the sharpe
machined ridge where the machineing meets the cast bowl below the seat. You want to enhance the airflow path along the common, long port wall/ roof area and past the valve guide boss.
Thin and streamline the valve guide boss in the port. The long side port wall needs to be straightened but not much. The area where the two ports pass the bolt hole is thin here.
Blend and radius the short side radius from just below the valve seat to the port floor. Remove the rough cast surface but do not polish the intake port at all.
On the exhaust side enlarge and blend the bowl area under the valve seat and radius and blend the short side radius.
Streamline and smooth the valve guide boss and smooth and clean up the rest of the port. Exessive enlarging or reshaping the exhaust port is not nessessary or desireable. Polish the exhaust port to your hearts desire. The combustion chamber only needs to be debured smoothed and polished. Have a three angle valve
job done after your done. Forget the flow bench figures. Follow these basic easy to do guidelines and you'll have good street/ strip power increase results on any of the chevy heads.

 

Really, buy the book, it will pay you back
10 fold in terms of "time saved"
and perhaps that much again
in terms of saving money on things that
don't matter

 

Here you go dude it 15.00 bucks for the book.

http://half.ebay.com/cat/buy/prod.cgi?cpid=2821705