Now that we have our lathe arbor made and our initial measurements taken we are about ready to shave the head. One final measurement should be taken to assist in knowing how much material is being removed from the head. Mark a reference spot on the cylinder head that can be used each time when taking a measurement. Put the straight edge across the machined surface of the head and use the dial calipers to measure the distance to your reference spot. In this example when this measurement is .080" less then our initial measurement I will know that I remove the correct amount of material.
 
 

Reference measurement for machining.

Arbor chucked in lathe with head attached.	Machining the surface of the head.
Measuring amount machined.	Final result. Mark amount taken off head for future reference.
Machined head on left. Unmodified head on right.	Another angle for comparison.

After the machining is completed it is best to stamp or permanently mark the head with the amount that has been removed. This will allow future owners or yourself know that this is a modified head.