View single post by Judson Manning
 Posted: 06-10-2007 02:29 am
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Judson Manning



Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
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 The new Goetz(sp?) head gasket is about .020" thicker than the original steel-asbestos version.  It adds a bit of insurance when it comes to piston to valve clearance. 

With stock cams, running the CP or JE pistons with a decked head is not something to worry about.  I wouldn't be concerned with the 107 either as I'm running a custom grind which has slightly more lift than the 107.  I've not personally run a cam with as much lift as a 104, but I'm sure there are enough club members with 104 cams and JE pistons who could lend their experiences.

Technically the service limit is ~.015", but as Jon points the real limit is the point where the valve seats start to be machined.

The fact is you want the head flat so it seals well.  The head alloy is quite soft and tends to deform when torqued down on the original steel head gasket, so it's almost a foregone conclusion that every head needs to be skimmed. 

The "9.5:1" pistons actually spec out in the engines I build somewhere in the 10-10.5:1 range.  With this already high c/r, there's no need to do anything but deck the head sufficiently to get a flat surface.