Abstract: A timing apparatus for an engine having a drive shaft and a gear box shaft parallel to the drive shaft. Each of the shafts having a toothed wheel eccentrically keyed thereto. The toothed wheels engaging each other so that when the gear box shaft rotates at a constant speed, the drive shaft runs half a turn at a minimum speed and half a turn at a maximum speed.

Abstract: Timing apparatus for a four-stroke engine with at least a shaft (2) of cams (7) located over the head of the cylinders and with the cams (7) acting directly on the valves (4), wherein the rotary motion of each shaft (2) of cams (7) is derived from a transmission shaft (1) parallel to the camshaft and driven by the engine crankshaft through a pair of identical gears (3,30) which are eccentrically keyed, one (3) on the transmission shaft (1) and the other (30) on the shaft (2) of cams (7), and are also 180.degree.-out-of-phase to one another, and with the cam (7) which is provided for the opening of the relevant valve (4) keyed on the shaft (2) of cams (7) having the maximum radius (r2) lift in phase with the minimum radius (R2) of rotation of the corresponding gear (30) eccentrically keyed on he same shaft (2) of cams (7).