how big? cylinder heads

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65notch

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Jun 18, 2005
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661 Cali
well its time to upgrade the heads on my 289. ive read through some of the previous threads on choices and i know whats out there. but how big should i go? im got a rebult bottom end. bored 30 over with flat top pistons. ive read that if i go to big on valve size i can cause some piston to valve probs. also, chamber size, right now im running 9.2:1 compression on the stock heads. how should i chose the new champer size. so sombody help me out here. thanks
o yeah. this is a street car...
 
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ok im answering my own question here. im readin on edlebrocks site that 1.90 IV is the biggest i can go with stock pistons..which i belive would be flat top?

now im trying to put together all the parts ill need to do this headswap...im lost on the head gaskets...im not sure what size to get? or what material the should be?
 
I don't think this is getting many responses as its in the classifieds section.

To be on the safe side, you would want to measure the valve cuts to make sure. If its a stock piston, someone would probably be able to answer that but I have no idea. If they are aftermarket, they are more than likely okay as they would be a minimum of 1.94 for the intake, 1.6 for the exhaust (not every aftermarket piston but most).

As far as new heads are concerned, you are going to need something small. I believe the stock 289 chambers are 54cc. You need this size chamber on an iron head and roughly 52cc for an aluminum to compensate for expansion. This a bad idea on any aluminum head as most are cast at 58-60cc. If you milled the head that much you would have intake alignment problems and if wanted to switch heads, few people want a chamber that small.

IMO, I would keep your 289 heads and learn to port if you have the time or have someone port them. An average good port job would be around $500.

The generic 289 head gasket is the 8542, the "hi-po" version is the 9333.
I believe the 8542 is a compressed thickness of .039" while the 9333 is .047". Slight loss of static compression but both good head gaskets.
 
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