MSD 8975 Digital Multi-Retard Installation - Manual (Page 2)

INSTALLATION INSTRUCTIONS
M S D I G N I T I O N
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PROGRAMMING
CylInder SeleCt
The Digital Retard is programmed at the
factory for operation on 8-cylinder engines.
If installing the Control on a different style
engine, the number of cylinders will need
to be selected on the Cylinder Select Dial
(Figure 1).
MagnetIC CoMPenSatIon CIrCuIt
This circuit provides a timing compensation for different style magnetic pickups. Magnetic pickups can
have varying thresholds and being able to program the style pickup you use provides a more accurate
and stable timing signal. This adjustment is more important for engines using crank triggers or locked-out
distributors. If you are using the White wire to trigger the MSD, no adjustment is necessary.
Note: It is recommended to check your Total
timing to ensure the best setting for
your application.
Start retard
When programmed, the Start Retard will
retard the timing during cranking to ease
starting. The amount is adjustable with the
rotary dial on the side of the unit (Figure
2). The retard will be activated only during
cranking and will remain activated until
the engine reaches 800 rpm where it then
returns to the set mechanical timing. If the
engine speed drops below 500 rpm, the Start
Retard will activate again.
retard rate
There are four different stages of retard that are activated by individual wires. When the corresponding
wire is removed from ground that retard amount is activated. Each retard selector switch is adjustable
from 0° to 9° (Figure 3).
When more than one channel is activated at
a time, the retard amounts are cumulative
(Example: 4° on the first stage, 3° on the
second and 3° on the third equal a total of
10°). The total amount of retard that can
occur is 20° even if it is programmed for
more.
Note: If you are not using all of the retards,
set the rotary dial to 0° or ground the
inactive circuit's activation wire(s).
Figure 1 Programming the Cylinder Select.
Figure 2 Programming the Pickup
Compensation and Start Retard.
Figure 3 Retard Stages and Activation Wires.