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LS3 head gasket question

Old Mar 22, 2022 | 06:54 PM
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Default LS3 head gasket question

Boring an LS3 out to 4.07 am I able to use a stock LS3 head gasket? Using L92 heads, no milling. Pistons I am looking at are JE 311981. I do not believe I will have PTV issues with this setup.
Just wondering if I can use the stock LS3 gaskets in terms of bore size?

I believe that the LS3 gaskets have a bore of 4.085? Can anyone confirm that as well?
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Old Mar 22, 2022 | 11:11 PM
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im 99% sure your correct.
Sorry i dont have any stock gaskets to double check
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Old Mar 22, 2022 | 11:12 PM
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Ees okay buddy
Nobody on LS1Tech answered my question
Guess I need to call someone up haha
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Old Mar 22, 2022 | 11:18 PM
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Yes, you can use those gaskets.

The idea is that you don't want the gasket to over hang the bore.
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Old Mar 22, 2022 | 11:19 PM
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I just didn’t know how acceptable it was for the gaskets to be bigger than the bore.
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Old Mar 22, 2022 | 11:25 PM
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Originally Posted by shakenfake
I just didn’t know how acceptable it was for the gaskets to be bigger than the bore.
Well you do want them larger than the bore. The closer they get to the edge, The more they are going to be subjected to the flame front.

I don't know what the margin of safety is.
But For example, GM states the original 6.0L gaskets are safe for a .020 over bore. The gasket is still larger than that. But I have never measured the bore on any of the aftermarket replacements to see if they are any larger than the OE.
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Old Mar 23, 2022 | 12:13 AM
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Gotcha LS9 head gaskets are probably the way to go then since they are 4.100
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Old Mar 23, 2022 | 09:47 AM
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Originally Posted by shakenfake
Gotcha LS9 head gaskets are probably the way to go then since they are 4.100
Yea cause everybody uses LS9 head gaskets on 4.8/5.3s.
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Old Mar 23, 2022 | 10:25 AM
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@RDF1 Oh yeah that just seems so wrong to me. I'm not an engineer but a 4.1" bore gasket on a 3.78" cylinder seems way big. Not an engineer though so couldn't tell you if that was the right or wrong way to do it.
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Old Mar 23, 2022 | 12:18 PM
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it is some lost space and thus lowered compression for sure. But for the price, LS9 gaskets can't really be beat
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