How to lower compression???'s

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dickeymoore

G-Body Guru
May 6, 2009
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Atlanta,Georgia
I just picked up a rebuilt sbc 406 engine and when i removed the heads it has TRW L2311 forged pistons in it that will give me 13.4 compression with my 64cc heads,is there a sbc 400 thicker headgasket with steamholes that I can use to try to get this engine pump gas friendly maybe 11.5 or lower?THANKS
 

64nailhead

Goat Herder
Dec 1, 2014
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Not with a headgasket. You could pull the pistons and have them milled and/or make the head chambers a little larger.

Are you planning to race this or just street drive?

What’s the current deck height?
 
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Oct 14, 2008
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Melville,Saskatchewan
SBC heads are cheap and larger CC should be readily available, go that route.
 

565bbchevy

Geezer
Aug 8, 2011
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There are a lot of variables for compression ratio, but I think max you will drop will be around 12:1 with even the largest cc performance head.
 
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Oct 14, 2008
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It looks like a 75 or 76cc is the biggest available with reasonable sized runners. The 80cc heads have 235 or 245cc intake runners, huge.
 

565bbchevy

Geezer
Aug 8, 2011
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IMO if you are going to try to make this a pump gas 400 SBC I would replace the pistons with a Hypereutectic or forged piston with lower compression, I think even if your current pistons are a solid dome you still probably won't get below 12:1 with milling and they might also be hollow dome.
 
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