Service manual

IGNITION SYSTEM
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 4B-5
Description
EST or Electronic Spark Timing is a High Energy Ignition System (HEI). The distributor itself
has no centrifugal advance mechanism or devices.
The spark plug wires are a carbon-impregnated cord conductor with a silicone rubber jacket.
It is important they be handled with care, and routed so as not to cross each other or to be
in contact with other parts of the engine to prevent rubbing.
The EST System uses a square coil with epoxy covered windings to protect against mois-
ture and arc-over.
The timing cannot be set the same way that other ignition systems were.
70106
b
c
e
d
f
a
a-Distributor with Spark Plug Wires
b-Wires (WHITE) Used in Timing Procedure
c-Wire from Shift Interrupt Switch
d-Distributor Harness
e-Engine Harness Wire (PURPLE AND GRAY)
f-Coil
EST uses a magnetic pulse generator and an electronic module to primary circuit current.
Internally the Pulse Generator, or magnetic pick-up assembly, takes the place of conven-
tional points. A timer core on the main shaft of the distributor has external teeth which align
with an equal number of pole piece teeth (four for a four cylinder engine). The electronic
module is small enough to allow it to be mounted inside the distributor, and contains the cir-
cuits necessary for dwell control and advance of the timing.
Index