Ignition System - HEI (Federal): Description
The Delco-Remy High Energy Ignition (HEI) system consists of the ignition coil, spark plugs, distributor assembly and primary and secondary wiring.
The distributor housing contains an electronic control module, pick-up coil, pole piece, timer core, rotor, capacitor for radio noise suppression and timing advance mechanisms. Most applications house the ignition coil assembly within the distributor cap. See Fig 1 . Full battery voltage is present at the battery terminal of distributor cap in either the "START" or "RUN" position. Ballast resistance is not used in the primary system.
Chevrolet and GMC light trucks with 5.0L 4-Bbl. (VIN H) engines are equipped with Electronic Spark Control to suppress detonation. ESC models have 5-terminal electronic modules in the distributor and non-ESC models use 4-terminal modules.