Abstract: A method and apparatus for fitting, by a manipulator, a cylinder head to an engine block in proper registry relative to each other through engageable locating pins and recesses prior to assembling rigidly with a plurality of coupling bolts into one whole integral body in an automatic assembling line. The engine block is formed with bolt engaging bores and is placed on the main assembly line. Coupling bolts are inserted through bolt receiving bores formed in the cylinder head with the bolts protruding. The cylinder head is brought from an auxiliary assembly line and set on the engine block while inserting the protruding coupling bolts into the bolt engaging bores and thereby the cylinder head is securely, albeit temporarily, held on the engine block pending tightening of the coupling bolts even if the locating pins and recesses are not perfectly aligned.