Electronic spark timing advance and emission control system

An electronic spark timing advance and emission control system for a pulsed electronic ignition control unit for emission controlled internal combustion engine includes a distributor having a pair of speed responsive, signal generating pickups and a pair of electronic spark timing control channels each of which is excited by a different one of the pickups. One of the channels is operative only during engine starting intervals and triggers the electronic ignition control unit with pulses of fixed or invariable timing at the optimum starting angle of the engine in advance of the TDC position thereof. The other channel is a variable timing control channel, which is operative after starting and during engine idle and run conditions, and provides ignition triggering pulses whose occurrence in time is varied from the TDC engine position at engine idle to provide any desired degree or requisite amount of spark timing advance or retardation therefrom during off-idle engine operating conditions in accordance with various engine operating parameters, including engine speed and manifold vacuum.