Ignition System - HEI-Est: Description
The Delco-Remy High Energy Ignition Electronic Spark Timing (HEI-EST) system consists of distributor housing, rotor, cap, 7 or 8-terminal ignition module, magnetic pick-up, pole piece, pick-up coil, connecting harness and the EST portion of the ECM. On some models, the ignition coil is contained within the distributor cap, while others have an externally mounted coil. See Fig 1 and Figure . A capacitor is installed in the distributor for radio noise suppression.
No vacuum or centrifugal advance mechanisms are used. All spark timing changes are controlled by the Electronic Control Module (ECM) based upon monitored input signals. Some models use an additional Electronic Spark Control (ESC) ignition retard system in the event of engine detonation (knock). Most models are equipped with sealed ignition coil and ignition module connectors. See Figure.