Apparatus for controlling valve timing in an internal combustion engine locates a first valve port in a first side of the engine cylinder and a second valve port in a second side of the engine cylinder. A first rotating valve disc and a second rotating valve disc are respectively disposed next to the first and second valve port. Each rotating valve disc includes a valve port. Each disc rotates in synchronism with the crankshaft to align its' port with the respective first and second valve ports. A variety of intake devices coupled to the first rotating valve disc control intake air flow into the engine cylinder, and a variety of exhaust devices coupled to the second rotating valve disc control exhaust gas flow from the engine cylinder.

In an internal combustion engine, first and second rotating members, one for the intake valve and one for the exhaust valve rotate next to the outside of an engine cylinder on opposite sides thereof when driven by a drive gear attached to the end of the engine's crankshaft. Each rotating member may include a ring gear having a valve port or aperture near its perimeter that cyclically aligns with a corresponding valve port formed through the cylinder wall near the top of the cylinder. A method of controlling valve timing comprises the steps of causing the rotating member containing the second valve port to periodically align in synchronism with the first port to control the passage of an air/fuel mixture and exhaust gases through the combustion cycles of the engine.