A profilometer was used to determine the surface finish. The standard of surface finish measurement is the microinch. Literally, one microinch means one-millionth of an inch. No surface is ever perfectly smooth. Machined surfaces have thousands of minute grooves of various depth. A profilometer is used to identify the surface finish. This instrument traverses a stylus back and forth over the area to be checked and automatically computes the average depth of the grooves. The readings can be taken in different scales. RaceKrafters uses the RA standard.
The science of surface finish is an area of interest to the crew at RaceKrafters. The texture of the surface is paramount to piston ring and cylinder head gasket seal. Craig achieved an RA number of 20, 15, and 12 for the block deck, cylinder head, and bore, respectively. The cross-hatch on the cylinder wall will be 35 degrees. View Related Article