[911pcars]

IMHO, the important spec to identify is the deck height. The ideal deck height provides the minimum squish area around the periphery of the piston @TDC while maintaining adequate clearance between piston and cyl. head. Spacing the cylinder changes the relationship between piston and cyl. head.

In addition, machining operations to square up the crank and crankcase, renew cylinder and cylinder head contact surfaces, equalizing cylinder heights, etc. all add up to decrease the deck height. As mentioned, additional or thicker cylinder base gaskets can restore the proper deck height, but I wouldn't use this method to remove slack from the timing chain. The "stack" height is what it is due to the material removed in the above operations.

Also, the total reduced stack height is the amount to remove from the chain box-to-crankcase gasket surface in order to re-center the camshaft in the chain box, otherwise an oil leak will develop due to the off-center cam.

If all cylinder components are equal and square with proper clearances and the timing chain slack increases after all is said and done, then deal with the longish chain at the idler arm/sprocket end. I would recommend a larger idler sprocket in this case.

And to answer the initial question, yes. If the machining operations affect the cylinder/combustion chamber volume, it will affect the compression ratio.

Comments?

Sherwood