Ignition System - HEI-Est: Description
The Delco-Remy High Energy Ignition (HEI) system with Electronic Spark Timing (EST) is a self contained unit. The distributor consists of the housing, rotor, cap, magnetic pick-up, pole piece and pick-up coil. The ignition coil is contained within the cap except for 4-cylinder engines which have an externally mounted coil. 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 electronically controlled ignition retard circuit in the event of engine knocking or detonation. Distributors with externally mounted ignition coils may be equipped with sealed module connectors. See Figure.