MSD 8365 GM HEI Billet Distributor Installation - Manual (Page 7)

INSTALLATION INSTRUCTIONS 7
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VACUUM ADVANCE LOCKOUT
If you do not want to use the vacuum advance canister,
MSD has supplied a lockout mechanism.
1. Remove the three Phillips screws that hold the
advance canister (Figure 12).
2. Remove the aluminum hex shaped spacer from
the housing.
3. Install the longer hex spacer supplied in the parts
bag in the threaded hole next to where the original
spacer was mounted. Use the same Phillips
screw.
4. Install the plastic cover to seal the distributor
housing using the original advance hold down
screws (Figure 13).
Note: Do not forget to plug the original vacuum
advance hose.
VACUUM ADVANCE ADJUSTMENT
A kit is supplied that allows you to adjust the total
amount of vacuum advance.
Figure 13 Vacuum Lockout Installed.
Figure 12 Removing the Vacuum Canister.
VACUUM ADVANCE HOLE
(NOT USED)
LONGER
HEX SPACER
LOCKOUT
COVER
CANISTER
SCREWS
HEX
SPACER
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).
No Rev Limit: To disable the rev limit function, cut and remove the
jumper shown in Figure 14.
PROGRAMMING THE REV LIMIT
A tachometer is required to set the rev limit. The limit is programmed
by running the engine at half the desired rpm, then momentarily
grounding the Gray tach output wire from the MSD. A Gray jumper
wire is supplied to connect to the tach with another tee-splice
coming off to use for programming. A switch may also be installed
to ease adjustments of the limiter (Figure 15). The default rpm limit
is 10,000 rpm. Note that the rpm limiter is extremely accurate and
due to the variety of tachometers available, there may be differences
in the displayed rpm.
1. Start the engine and bring the rpm to half the desired rev limit
(for a 6,000 rpm limit, raise the rpm to 3,000).
2. While holding the rpm steady, short the Gray tach wire to ground
for approximately one second. Note that the tach will go to zero
while grounded.
3. The tach will now display the programmed rev limit amount for
two seconds. If this value does not register on the tach, repeat
the procedure and try a different ground source.
Figure 14 Disable the Rev Limit.
JUMPER
TO
TACH
OPTIONAL
PROGRAMMING
SWITCH
JUMPER GRAY
Figure 15 Setting the Rev Limiter.