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Ls3 cylinder head milling

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Old Sep 30, 2009 | 03:13 AM
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Default Ls3 cylinder head milling

I need some advice, I have an 08 C6 with an LS3 my current mods are HPE megadeath cam kit, kooks 1 7/8 headers, off road x pipe, stock cat back, pulley, ported throttle body and callaway air box this cambination made 490rwhp. My question is, can I mill the heads to gain some compression and how much can I mill them without having problems with piston to valve clearance.
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Old Sep 30, 2009 | 01:31 PM
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Originally Posted by SUNSETLS1
I need some advice, I have an 08 C6 with an LS3 my current mods are HPE megadeath cam kit, kooks 1 7/8 headers, off road x pipe, stock cat back, pulley, ported throttle body and callaway air box this cambination made 490rwhp. My question is, can I mill the heads to gain some compression and how much can I mill them without having problems with piston to valve clearance.
i never go more than .030 on any oe ls head. if u mill the heads any it is a strong possiblity that u will have ptv clearance issues with that cam.
if u mill the heads, u will also have to cut in valve relieves. and scr depends what gasket used.
need to cut in relieves, measure cc of material removed, and then decide amount to mill using the volume value of the gasket used, for desired scr.
.030 would be the max i would cut down, due to intake manifold and heads aligmnent. and i would also check pushrod length as well after all has been assembled again.
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Old Sep 30, 2009 | 08:50 PM
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I agree .030 would be the max. I did this and had some alignment intake issues. I had to cut the tab on the intake for it to bolt down. I would also consider a new set of intake gaskets so they are nice and thick. Keep in mind there is a slight off angle at the bottom of the intake due to the milling. Thats why I recomend the new gaskets.
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Old Oct 1, 2009 | 12:20 PM
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I don't think it would be worth it to me to pull the heads just to mill them a little.

Mine are milled .030 and measured 64cc. My intake fits fine because I made it after the heads were milled.
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Old Oct 1, 2009 | 06:19 PM
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What about having a set of ported LS3 heads welded up (adding material to the chambers until they are at the desired cc) and then re-hardened?

Or maybe a set of Mast Motorsports aftermarket 12degree LS3 heads?
Maybe they have one available that would have both better flow rates as well as smaller chambers to both boost compression and performance???
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Old Oct 1, 2009 | 06:23 PM
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Originally Posted by Bring the Noise
What about having a set of ported LS3 heads welded up (adding material to the chambers until they are at the desired cc) and then re-hardened?

Or maybe a set of Mast Motorsports aftermarket 12degree LS3 heads?
Maybe they have one available that would have both better flow rates as well as smaller chambers to both boost compression and performance???
easier to pay for smaller chamber aftermarket heads. if really need to raise scr or prolly even cheeper to use dome pistons with existing heads
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Old Oct 1, 2009 | 09:45 PM
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good info
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