PURPOSE: To make an engine in small size by providing a swash plate cam at a part of a rotary follower mechanism and driving the mechanical pump by rotation of this swash plate cam.

CONSTITUTION: A swash plate cam 5 is formed solidly at the side face of a distributor driving gear 3, which is mounted at the tip of a cam shaft 2 following rotation the engine, and a push rod 12 of the mechanical pump 9 shall be placed in contact with this swash plate cam 5 so that the mechanical pump 9 is driven by rotation of the swash plate cam 5. This constitution does not require use of any eccentric cam nor long dimensioning of cam shaft and casing, so that the engine can be designed in small size.