PURPOSE: To provide a working process which makes it unnecessary to work over again the joining surface of a cylinder head even if the joining surface of the cylinder head located in the opening part of a sleeve is strained when the inner peripheral surface of the sleeve provided in the cylinder block is worked.

CONSTITUTION: The rough working of the joining surface 3 of a cylinder head, rough working of the inner peripheral surface 7 of a sleeve 2, finishing work of the inner peripheral surface 7 of the sleeve 2, honing work of the inner peripheral surface 7 of the sleeve 2, and finishing work of the joining surface 3 of the cylinder head are carried out in the mentioned order.