MSD 6520 Digital 6-Plus Ignition Control Installation - Manual (Page 6)

6 INSTALLATION INSTRUCTIONS
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REV LIMITER
There are two adjustable rev limits that you can adjust; the Max Limit and the Two Step Limit. Both limits are
adjusted in 100 rpm increments by turning the rotary switches on the side of the Ignition (Figure 4). Note:
The engine can be running as you make adjustments to the rev limiter and retard function.
Max Limit: This is the overrev rpm limit. The Soft Touch circuitry will begin dropping the spark to cylinders
any time the rpm reaches the amount you select, except if the Two Step Limit is activated (12 volts applied
to the Blue wire). The limit can be adjusted from 2,000 to 9,900 rpm. Setting both dials to Zero defaults to
a limit of 12,500 rpm.
Figure 4 Adjusting the Rev Limits.
Figure 5 Wiring the 2-Step Rev Limit.
Figure 6 Wiring the Retard Stage.
2-Step Limit: This rpm limit is activated
when 12 volts are applied to the Blue
wire. When activated, this limit overrides
the Max Limit. This limit is adjustable from
2,000 to 9,900 and will default to 2,000 rpm
if the dials are set to an rpm below this
range. An example of wiring the 2-Step
Limit so it is activated with the line-lock is
shown in Figure 5.
RETARD STAGE
The MSD features a single stage retard
step that is activated when 12 volts are
applied to the Pink wire. The retard will
remain until the 12 volts are removed.
This retard step can be connected to
a nitrous solenoid activation wire or
micro-switch on the shifter. The retard
is adjustable from 0° to 9.9° in 1/10°
increments. The example in Figure
6 shows connecting the retard to a
nitrous stage.
Note: This retard will only operate
above 2,000 rpm.