nuck

I milled the heads on my LS7 .030. If in the future I decide on maybe a 5psi Maggie can I run the over-thick Conetic gaskets? Has anyone tried?

lt1z

Why would you want to ruin the quench?

C6 Curtis

You will still be fine, 5 psi isnt much.

nuck

Thanks for the responses. Yeah 5psi isn't much but I thought the stock compression was already way too high for boost.

Why would returning the combustion chamber to stockish volume ruin the quench? I think the factory gasket is .051 so the .080 essentially returns the stock compression right? Is the .030 milling somehow beneficial?

lt1z

Because you are not doing anything to the chamber it self which has already been reduced in size by milling. Now you ate trying to cheat compression back down by thickening the gasket which raises "quench" which is piston to head clearance and not desirable.

What you want to do is sell the heads and start over with a head that allows you to to run a GM gasket.

nuck

I'm confused. Isn't the quench just the distance between the top of the piston and the flat part of the cylinder head chamber? So milling .030 and then adding a .030 thicker gasket should result in an identical combustion chamber layout to an unmilled head with stock gasket. Piston top distance to the head should be the same in both cases with the only difference being a few thousandths more gasket edge being exposed in the combustion chamber. Or am I missing something?

lt1z

Yes you are missing something. It is not the same to add .030 to the gasket thickness and that will screw up the quench which can lead to tuning issues amongst other thing. You could port the chambers to try and lower compression but in the end the best thing would be to sell your heads and start over with un milled heads.

old motorhead

Run it like it is. You can add a meth system and/or change the camshaft if you're that worried about it. Either would be easier than pulling the heads off. An LS9 camshaft (or a properly specced custom grind) would probably put you right back to the same DCR that you started with. Meth would give you enough added octane that that the compression bump wouldn't be an issue. 5psi shouldn't be a problem anyway if the tune is right and you have plenty of fuel.

Kadorja

I can see what lt1z is saying about hanging the shape of the combustion chamber. Removing material slightly decreases the overall size (length, width and depth) but honestly like it's been said before with boost and adding meth quench isn't as big of an issue. There's already good compression and the meth should deal with any detonation issues.

lt1z

I guess what I am saying is there is a right way to do things and a zip ties and duct tape way to do things.