5.3 vs 243 Heads...Confusion
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5.3 vs 243 Heads...Confusion
I have been told swapping heads on a 5.3 with 243 LS6 heads will increase my combustion ratio. But after some checking, i noticed that the 243 heads have a larger combustion chamber. Do i have the wrong information or what, i am confused. Please help.
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Originally Posted by tdrumm
Yeah, 5.3 heads have a 61cc chamber v. 65cc for a 243 head. So unless you mill them down, you'll loose compression. 243s do flow a lot better though.
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Originally Posted by pbraxton
how much should be milled and is that within tolerance for the intake manifold mounting.
If you want to mill them, you'll need to shave off .055" to retain your compression. And yes, your intake will still bolt up, but you might want to shave that down a bit for best results.
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Originally Posted by silent1
Go with a thinner head gasket. Stock gaskets are .055, if you go with a .040 you'll be pretty close to your desired CR.
If you want to mill them, you'll need to shave off .055" to retain your compression. And yes, your intake will still bolt up, but you might want to shave that down a bit for best results.
If you want to mill them, you'll need to shave off .055" to retain your compression. And yes, your intake will still bolt up, but you might want to shave that down a bit for best results.
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Originally Posted by silent1
Do you only want to raise your compression? How much do you want to spend? Which cam do you have or plan on getting?
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If it's within your budget, ported/milled LS6 heads are a better choice. You can do a moderate mill, .030" and a thinner head gasket, .040". That'll bump your CR a bit, better quench, and better flowing heads. Ported 5.3 heads will also net you nice gains though.
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Originally Posted by pbraxton
how much should be milled and is that within tolerance for the intake manifold mounting.
Unported LS6 heads milled down to 58.8cc chambers with a 3.910 bore x .045 thick gasket on a stock 5.3 shortblock will net you ~10.0:1 compression.