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6Y-8 ENGINE ELECTRICAL
Pickup Coil
i
Timer Cire
Pole Piece
Figure 2-HEI Schematic
The electronic module delivers full battery
voltage to the ignition coil, which is limited to
5.0 to 5.5 amps . There is no primary calibrated
resistance wire in the HEI system . The elec-
tronic module acts as an "ON -
OFF"
switch
for primary current, triggered by changing
polarity of pick-up coil voltage . There is no
energy lost due to breaker point arcing or
capacitor charging time lag. The capacitor in
the HEI unit functions only as a radio noise
suppressor .
The higher current and instantaneous circuit
triggering enables the HEI system to deliver up
to approximately 35,000 volts through the
secondary wiring to the spark plugs.
An exploded view of the HEI system is
shown in figure 4 .
Secondary
Wire
(To Spark
Plug) ~
5
_
Figure 3-HEI Basic Wiring Diagram
SERVICE OPERATIONS
SERVICING PRECAUTIONS
NOTE .
For
HEI
systems,
engine
diagnostic analyzers using oscilliscopes will
require a special adapter and distributor
machines will also require modifications .
Major manufacturers of such equipment
have instructions on how such modifications
can be performed on their equipment .
The HEI system is capable of producing up
to 35,000 volts as compared to 25,000 volts
with conventional systems. Use care when
working with these higher voltages to avoid
contact with high voltage points such as spark
plug leads .
Care
should
be
taken when
connecting
timing light or other pick-up equipment .
Use
proper
adapters .
Do
not
force
contacts
between the boot and secondary wiring, and do
not puncture the silicone jackets (the high
voltage available will cause arcing from the
puncture point to ground) .
If secondary wiring is punctured or burned,
it must be replaced to prevent misfiring .
If
boots and nipples on the spark plug wires are
damaged, the arc will also go to ground,
causing misfiring .
Care
should
be
used
when
connecting
battery or in jump starting with the battery.
Reversing the connections or polarity could
cause damage to electronic module .
Also, do not operate the engine with _one _or
more spark plug wires disconnected . (To do so
may cause arcing to occur in the distributor
cap and cause carbon tracking .)
Do not ground the tachometer connection .
This could cause damage to the electronic
module . (Make certain that tachometer is
designed for HEI operation .)
When
making
compression
checks,
the
ignition
switch
connector
should
be
disconnected from the HEI distributor .
ELECTRONIC MODULE
The
electronic
module
is
serviced
by
complete replacement only . When replacing
the module, small "dabs" of special silicone
grease MUST be applied to the flat portion of
the module which will rest on the metal
mounting surface. If this grease is not applied
the module will not cool properly, which can
cause the module to malfunction. A tube of
this special silicone grease is supplied with
each replacement module . Make certain the
replacement
module
is
the
correct part
number.
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