A variable flow reducing valve and distribution system is disclosed for compressed air injection engines operating on mono or dual energy with dual or triple supply mode and comprising a high pressure compressed air tank and a buffer capacity. The system can control the stroke of an engine piston and stop the piston at the dead centre. Moreover, the air supply in the buffer capacity and to the cylinders is controlled by pilot valves. A cam for the pilot valves is positioned directly on the flanges of a crankshaft and drives the rocker arm rods to pivot rocker arms around corresponding mobile shafts that can move between two ends of the rocker arms, thereby controlling lifting of the pilot valves according to the movement of the rocker arm rods.