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Discussion Starter #1
So I just decided to the the head gasket on my pretty much stock 97 12 valve. Its got 280k on it and had just developed a really small leak under the thermostat housing of coolant to the outside. I got the head off and ordered studs and a top end gasket kit (stock thickness).

I had the head decked and he ended up having to take off .020''. My question is I realize I should have waited to order the head gasket but am I going to hurt anything by using a stock thickness gasket? I am not worried about the slight bump in compression ratio, what I would be worried about is the valve clearance to the piston. Any recommendations would be appreciated.

Thanks
 

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There will be no bump in compression. Yes you need to worry about the piston to valve. A thicker head gasket is the simple fix.
 

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Discussion Starter #3
Thanks. Do you know how much room you have to play with? Will I be okay or will they definitely hit?
 

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Milling the head does not effect compression, decking the block does.
Check to see how much the valves are recessed in the head.
Cummins min valve depth spec is .039, max is .060.
If they did a valve job it would have lowered the valves some.
I would have the valves reworked before going to a thicker gasket lowering compression.
Thicker head gasket's are 3 times the price of standard
My block was decked .010, .010 thicker head gasket was over $150, stock is under $50
 

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Discussion Starter #5
Thanks, yeah I guess I am still living in gas world where all the heads have the combustion chamber in them so normally when you deck the heads the compression goes up because you end up making the combustion chamber smaller.

I ended up ordering a .020'' over gasket just in case, it wasnt to bad, $70 bucks for victor whatever from xdp
 

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It's you truck but I thing you'll hate how much harder it will be to start on cold mornings with the lower compression.
 

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Discussion Starter #7
Shoot, I still have the grid heater on it. I also live in NC where most of the time it really doesn't get that cold. It has never even thought about not starting well in the winter here. Thanks for the advice and I'll have both gaskets to choose from after I go talk to my machinist a little more.
 
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