Head gasket bore size

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Oct 3, 2013 | 08:49 AM

ihdude

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From: Pineville, KY

Head gasket bore size

Building a 408 with AFR heads. On the head gasket I'm wanting to run a .040 thickness. What bore size of the gasket should I run?

Oct 3, 2013 | 04:22 PM

RezinTexas

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From: Katy, TX

measure your cylinder bore and head combustion chamber width. Then get a gasket bore that is at least 0.020" bigger than the larger of those 2 measurement.

Oct 3, 2013 | 05:09 PM

Dmoney

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From: laredo,tx

I use a .040 thickness 4.06 bore Cometic gaskets on my 402. A friend of mine uses a 4.085 on his 408.........

Oct 3, 2013 | 10:37 PM

2000PewterT/A

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Quote:

Originally Posted by RezinTexas

measure your cylinder bore and head combustion chamber width. Then get a gasket bore that is at least 0.020" bigger than the larger of those 2 measurement.

x2 This is what I do also.

Oct 4, 2013 | 04:58 PM

Russ K

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Quote:

Originally Posted by RezinTexas

measure your cylinder bore and head combustion chamber width. Then get a gasket bore that is at least 0.020" bigger than the larger of those 2 measurement.

Same here, but I use a gasket bore the same size, or just the next size larger. Cometic lists 4.040,4.060 then jumps to 4.100.

Russ Kemp

Oct 4, 2013 | 05:53 PM

dr_whigham

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I believe AFR specifies what size gasket to run with their head. A lot of times it's larger than your bore.

Oct 6, 2013 | 04:39 AM

moosifer

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I run the ls9 gasket on my 408 (4.030 bore).

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Oct 6, 2013 | 06:45 AM

dr_whigham

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Quote:

Originally Posted by RezinTexas

AFR makes great heads, however I would not take their direction on gaskets. They told me to us a 4.135" bore gasket with my 210 heads (which have a 3.96" cc width).

I know. It seems they always tell folks to go big on the gaskets, and I've never understood why. You think that "dead spot" would just pack with carbon and create detonation... There has to be some reason why they say that though?

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Head gasket bore size

Head gasket bore size

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