Milling 5.3 heads to 59cc?

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Feb 17, 2013 | 02:08 PM

T/ALT1

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Milling 5.3 heads to 59cc?

I am putting together a 2000 ls1 and installing a TSP 233/239 cam along with ported 5.3 heads. I'd like to get these down to 59cc for more compression so I was thinking I would have to mill them .030 to get them down to where I wanted but figured somebody here would have more experience. This is a street/strip setup that will be more strip. I will also check ptv clearance and Flycut the pistons if needed. Thanks

Feb 17, 2013 | 02:11 PM

batboy

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You don't need to mill that much to go from 61cc to 59cc. It's approximately .006" per cc for milling LS heads.

Feb 17, 2013 | 02:28 PM

T/ALT1

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I thought they were 62cc's stock? So I would only need to mill .012 thousandths to get a set of 862's down to 59cc?

Feb 17, 2013 | 02:31 PM

Jay Gadsby

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What are the"rule of thumb" gains as far as compression is concerned? What can one expect from gaining a point if compression in general? I have some 5.3 heads I am going to be using as well and wondered if its worth it to mill. Thanks, not trying to thread jack

Feb 17, 2013 | 02:49 PM

T/ALT1

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It's only like 3% per point of compression which is roughly 10hp per point but it also adds torque and helps when adding larger cams that tend to bleed off cylinder pressure. Since most heads get milled after porting to make sure they are flat and will seal correctly anyways. It normally doesn't cost any extra to mill .005 or .012 so might as well take advantage of free HP and TQ.

Feb 17, 2013 | 02:57 PM

Jay Gadsby

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Nice. Thanks for the info!

Feb 17, 2013 | 03:20 PM

batboy

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According to the SmokeEmUp website, the stock 5.3 heads have 61.15cc combustion chambers. Don't know if your ported ones got massaged any in the chambers or not.