DELCO-REMY High Energy Ignition: Operation
The magnetic pick-up assembly consists of a permanent magnet, pole piece and a pick-up coil. The pole piece is stationary (unless advanced or retarded by vacuum advance unit) while timer core rotates with distributor shaft. When teeth of timer core line up with teeth of pole piece a voltage is induced in pick-up coil. This signals the electronic module to open coil primary circuit and fire spark plug. See Fig 1.
The module automatically controls dwell, increasing dwell with increasing engine speed. Dwell is not adjustable and periodic checks of dwell are not necessary. The HEI system features a longer spark duration which is desirable for firing lean and EGR diluted air/fuel mixtures.