Abstract: A double wheel roller 31 and a pair of outboard rollers 35 are positioned, respectively, along a pair of parallel tracks 25 disposed on a rocker arm 15 and a pair of parallel rails 37 disposed on a pair of support plates 39 disposed on opposite sides of the rocker arm 15, a control rod 49 is utilized to move the rollers 31 and 35 along the tracks 25 and rails 37 to vary the pivot point of the rocker arm 15, and thus vary the lift of an intake valve 7 or the amount the valve 7 opens and vary the amount of combustion air admitted to the cylinder 4, which cooperates with the amount and timing of fuel injected into the cylinder 4 and the timing of the spark to control the speed and power output of a fuel injection, spark ignition, engine 2.