The cylinder head of water-cooled engine has three structural forms: integral type, block type and single type. In a multi cylinder engine, if all cylinders share a cylinder head, the cylinder head is called an integral cylinder head; If there is one cover for every two cylinders or one cover for every three cylinders, the cylinder head is a block cylinder head; If each cylinder has a head, it is a single cylinder head. Air cooled engines are all single cylinder heads.