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. The capacitor is used for noise suppression.
All spark timing changes are controlled by the Electronic Control Module (ECM) and there are no vacuum or centrifugal advance mechanisms. Some models use an electronically controlled ignition retard circuit in the event of engine knocking or detonation. Some distributors with externally mounted ignition coils may be equipped with sealed module connectors. See Figure.