Ignition System - HEI-Est: Description
The Delco-Remy High Energy Ignition system with Electronic Spark Timing (HEI/EST) is a self contained unit. The distributor consists of housing, rotor, cap, magnetic pick-up, pole piece and pick-up coil. On some models, ignition coils are contained within the distributor cap and other models have an externally mounted coil. See Fig 1 and Figure. A capacitor is installed for radio noise suppression.
All spark timing changes are controlled by the Electronic Control Module (ECM). No vacuum or centrifugal advance mechanisms are used. Some models use an additional ignition retard circuit in the event of engine detonation (knock). Distributors with externally mounted ignition coils are equipped with sealed module connectors. See Figure.