Calculating desired head gasket thickness

What is the process of determining what head gasket thickness is needed ? I recently purchased a built short block and I’m having the heads resurfaced. The pistons selected specify a compression ration of 10.6:1.

Headgasket will also have an impact in Compression Ratio, because the area on the circle diameter of the gasket by the height (thickness of it) will give you the volume of the headgasket. To know the static CR you would need to know: the volume of the cylinder (piston from BDC to TDC), the volume of the combustion chamber in the head and the volume of the headgasket diameter and thickness. This is supposing the pistons are flat and get to the top face of the block.

Remember that head gaskets will squish a bit after you torque the bolts, so its kinda difficult to measure a gasket. Check the manufacture "diameter and thickness on the gasket characteristics".

Thanks. I will also ask the engine builder for input.

Also be aware that one of the primary things to consider with the head gasket thickness other than it's affect on compression is the quench distance or distance at the edges between the top of the piston and the bottom surface of the head where contact may occur, or at least where the closest position of the piston and head will be as this can be a likely place for detonation to start. At a minimum you would need to measure the distance the piston sticks out or in from the surface of the block at top dead center (pistons rock a bit so measure max and min and take the average as you rock the piston, or measure at the edge where the piston is inline with the wrist pin). The exact minimum distance will vary a bit depending on rod length, maximum rpm, etc. but normally .035" would be a minimum required distance with many OEM manufacturer head gaskets being .040" (1.0mm).

As far as compression goes - remember there is a difference between static and dynamic compression and the dynamic compression is more critical in your considerations than the static compression as you don't start building cylinder pressure until the valves are all closed (cam duration and timing are taking into account when calculating dynamic compression).