Compression on C90E heads
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Compression on C90E heads
Is the compression ratio on 1969 351w heads 60cc? Also is it possible to open them up to 62-64cc? Just wondering cause I have all the stuff for a build I'm doing and can pick up these heads really cheap but need atleast 62cc to reach the desired compression ratio. I'm new to the site and and would like to say hello to everyone and looking forward to learning from everyone. Thanks to all in advance, Chris
Lead Driver
Joined: Jan 2019
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From: N.W. Alabama
Depends on compression ratio, your wanting, but didn't say, have you cc'd the heads, to know what they are now, are you sure they are 69 heads, usually a little porting and thicker than stock head gasket will change compression, assuming the heads have never been messed with, at all, which is a guess unless you cc them, to find out.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
The chamber size is 60cc. A couple cc won't make or break anything, if the plan is swapping these on a late model motor the chamber size is fine, but the pressed in studs and lack of hardened valve seats(assuming they are all original) makes these less desirable as the cost of machine work to remedy these issues could end up costing more than just buying a set of remaned GT40 heads.
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I'm building a 387 out of a 92 model block already have everything except the heads an cam. With the 60cc heads comp ratio will be 10.23:1 with .080 thick gasket. I no I'm gonna hafta put harden seats in them I no a guy really well that owns a machine shop so that won't be a problem. But will that comp ratio be to high for iron heads on pump gas. With the cost of heads these days I can get them and have the work done for less than half the cost of a set of reman gt40s. Just wondering if it would be worth doing or will they cause me to loose power vs the gt40s or another set of aluminum heads. They are 69 heads the casting on them is C90E a buddy of mine has them
Last edited by CM76; Jan 22, 2022 at 09:54 AM.
Cargo Master
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I'm building a 387 out of a 92 model block already have everything except the heads an cam. With the 60cc heads comp ratio will be 10.23:1 with .080 thick gasket. I no I'm gonna hafta put harden seats in them I no a guy really well that owns a machine shop so that won't be a problem. But will that comp ratio be to high for iron heads on pump gas. With the cost of heads these days I can get them and have the work done for less than half the cost of a set of reman gt40s. Just wondering if it would be worth doing or will they cause me to loose power vs the gt40s or another set of aluminum heads. They are 69 heads the casting on them is C90E a buddy of mine has them
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