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-   -   Comp. change, head gskt. thickness ?? (https://www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/comp-change-head-gskt-thickness-298690/)

RGMEPP 03-31-2005 01:08 AM

Comp. change, head gskt. thickness ??
 
Soon to have the 6.0 LQ9 down for a cam. head gasket thickness is going down from .054 to .032. Before I go digging through my books, is anyone out there a wizard on this kind of stuff ?? How nuch increase in compression ??

Grey Silver 03-31-2005 03:10 AM


Originally Posted by RGMEPP
Soon to have the 6.0 LQ9 down for a cam. head gasket thickness is going down from .054 to .032. Before I go digging through my books, is anyone out there a wizard on this kind of stuff ?? How nuch increase in compression ??

The pistons in a stock LS1 motor come out of the hole about .010. With a .032 head gasket the piston will hit the head. If you want more compression shave the heads or put some pistons in it.

Green Thunder 03-31-2005 07:50 AM

Here is a compression calculator to help you with the math..
Compression Calculator

Yelo 03-31-2005 07:54 AM


Originally Posted by Grey Silver
The pistons in a stock LS1 motor come out of the hole about .010. With a .032 head gasket the piston will hit the head. If you want more compression shave the heads or put some pistons in it.

????


If the piston comes out .010 and the gasket is .032 then he has .022 clearance between the piston and the head....I think this is a little close for comfort myself and that he will REALLY need to check p/v clearance VERY CAREFULLY but the piston won't hit the head itself

Grey Silver 03-31-2005 12:07 PM


Originally Posted by Yelo
????


If the piston comes out .010 and the gasket is .032 then he has .022 clearance between the piston and the head....I think this is a little close for comfort myself and that he will REALLY need to check p/v clearance VERY CAREFULLY but the piston won't hit the head itself

No it won't hit untill you start it up. The clearance you refer to is called quench. Do a search in the internal engine section and you'll figure it out.

Yelo 03-31-2005 07:40 PM

How can a motor with .022 clearance between the top of the piston and the bottom of the head have piston/head interference ???

Maybe I'm just dumb here but it seems to me that even when started that there will STILL be .022 clearance.....even with heat expansion there should still be room, WHY would ANYONE make a gasket that would CAUSE the piston to touch the head ????

BigTex 04-01-2005 02:32 PM

It all depends on the duration of the cam and valve timing. If the valves aren't open too far when the piston reaches the top, then there isn't an issue.

I do agree however that the .008 negative deck height with a .033 gasket thickness is a pretty tight quench.

Grey Silver 04-02-2005 06:09 PM

[QUOTE=BigTex]It all depends on the duration of the cam and valve timing. If the valves aren't open too far when the piston reaches the top, then there isn't an issue.

I do agree however that the .008 negative deck height with a .033 gasket thickness is a pretty tight quench.

Let's forget about the valves for now, we can always cure that problem.

Are you saying that the piston will not hit the head at .022 quench on an LS1 motor?
If anyone decides to try this please be sure to let me know because I would like to hear how it works out for ya.


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