Its done with a profilometer, but most machine shops know the rate of feed, RPM surface speed of their machines and can make a pretty good guess on how to surface either the head or the block.

RIP Monte Smith

Your work is a reflection of yourself, autograph it with quality.

WD for Diamond Pistons,Sidewinder cylinder heads, Wiseco, K1 rods and cranks,BAM lifters, Morel lifters, Molnar Technologies, Harland Sharp, Pro Gear, Cometic, King Engine Bearings and many others.