Abstract: 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.