Abstract: A distributor for an internal combustion engine and associated methods comprise a camshaft having a drive gear thereon, a trigger disk positioned on the camshaft so as to rotate coaxially therewith, the trigger disk having a plurality of tabs defining a window between adjacent tabs, an optical sensor positioned relative to the trigger disk so that the plurality of tabs passes within sensor range as the trigger disk rotates on the camshaft, the sensor generating signals responsive to detection of the plurality of tabs, and a microprocessor operatively linked with the optical sensor and programmed with one or more ignition curves providing predetermined rates of ignition advance responsive to signals from the optical sensor.