An engine which employs a cam follower mechanism to reduce wear and reduce the size of an assembled engine. The cam follower mechanism utilizes guide rails located to reduce side thrust on the valve stem. The engine employs a high speed quill shaft to synchronize independent cam shafts existing in each of a plurality of interconnected engines. The engine is assembled using a single size fastener to provide a uniform stress gradient within the engine. The engines are interconnected utilizing O-ring seals. The engine provides a piston crown utilizing a connecting rod directly connected to the bottom surface of the piston crown. The piston crown is stabilized along the longitudinal cylinder axis by a rail guide. Connecting rods are provided which require less than one hundred eighty degrees (180°) circumference of a crankshaft pin for support so that a plurality of connecting rods can be associated with a single crankshaft pin. A tabbed bearing fits under the plurality of connecting rods to provide lubrication between the connecting rods and the crankshaft pin. Connecting rods are held to the crankshaft pin by a circular retaining ring. The engine provides a separate cylinder head and cylinder which are attached via a circular deformable retaining band to form a metal to metal seal. The engine provides an independent lubrication system in each engine. Coolant or lubricant is provided to each engine in parallel so that the temperature of the coolant entering each engine is the same. A large diameter modular crankshaft is provided.