MSD 83647 HEAT HEI Module Installation - Manual (Page 2)

2 INSTALLATION INSTRUCTIONS
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7. Connect the HEI Module harness to the Distributor Cap followed by the 12 volt (BAT) wire. This
wire should be at least 14-gauge (Figure 2).
8. Connect the long black wire to the engine block for a solid ground.
9. See the next page for tachometer and rev limit programming.
10. It is recommended to install the supplied low resistance rotor bushing. This improves the spark
transfer from the coil to the rotor tip. Remove the coil cover and coil. Replace the rotor bushing.
Figure 2 Connecting the Module and Tach Lead.
TO ENGINE
GROUND
LONG BLACK
TO TACH
OUTPUT
GRAY
TACHOMETER INFORMATION
The HEAT Digital HEI Module has a Gray wire that provides a 12 volt
square wave, 20° tachometer signal that will trigger most tachometers.
It is recommended to connect this lead to your tach’s trigger input
wire and check its operation. If the tach requires a higher voltage
signal, connect its input wire to the Tach terminal on the HEI Cap
(Coil-/Tach). Note that the rpm limiter is extremely accurate and due
to the variety of tachometers available, there may be differences in
the displayed rpm.
No Rev Limit: To disable the rev limit function, cut and remove the
jumper shown in Figure 3.
Figure 3 Disable the Rev Limit.
JUMPER