721.11 : Head Gasket
a. Unaltered B&S part #555723 is the only head gasket allowed.
b. Minimum thickness allowed is .047″. Measurement must be performed using a micrometer. Readings are taken from inside the cylinder hole of the gasket closest to the combustion chamber (see diagram). Four measurements are to be taken in the four defined quadrants with 3 meeting the minimum thickness of .047”.