a cylinder head for attachment to a block assembly of an internal combustion engine as a replacement for a conventional cylinder head and its conventional valves and associated mechanical components . the cylinder head includes at least one longitudinally disposed spool with ports therein . when the spool is rotated the ports are rotated in a timed manner to be in communication with fluid intake openings and exhaust openings to permit the inflow of fuel into a cylinder in the block assembly and the exit therefrom of exhuast gasses . the use of a spool with ports eliminates the need for conventional valves , thereby permitting a lighter and smaller cylinder head assembly , as well as enables an engine to operate more efficiently at higher than conventional rpms .