MSD 7330 7AL-3 Ignition Control Installation - Manual (Page 6)

6 INSTALLATION INSTRUCTIONS
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OPTIONAL WIRING
This Wiring Section details the optional features of the MSD 7AL-3 and
how to wire each system.
START RETARD
The Start Retard of the 7AL-3 is designed to ease cranking on engines
with locked timing, high compression and a lot of advance. The amount
of retard is determined by a plug-in degree module (Figure 8). There
are two different ways to activate this function (Figure 9):
A. Switched 12 Volts
In this set up, the timing is retarded only while the engine is cranking.
Connect the supplied Violet wire from the “Start-Retard” terminal on
the 7AL-3 to the starter solenoid. This way, 12 volts is only applied
when the key or switch is in the cranking position. When the switch
is released, 12 volts is removed and the timing returns to run timing.
B. Constant 12 Volts
In this setup, whenever the ignition is turned On, 12 volts is applied
and the retard function is activated. The retard will be removed when
the engine reaches about 600 rpm
and will not occur again until the
ignition is turned Off. Connect the
supplied jumper from the Start-
Retard terminal to the IGN terminal
of the terminal strip (two terminals
up).
THREE STEP RPM LIMITS
The 7AL-3 has a built-in Three Step
Module Selector which allows you
to select up to three different rpm
limits. The activation terminals
are located on the bottom of the
third terminal strip and are listed
as Launch and Burnout. The third
rpm limit is the high rpm, which is
always active when there is an rpm
module installed in the "Race" holder
(except when the other rpm limits are
activated).
These modules can be used in a variety
of functions and are not limited to
launches and burnouts. Each of the two
optional rpm limits are activated when 12
volts is applied to their corresponding
terminals (Figure 10). The 12 volts can
come from switches, solenoids or relays
giving you a variety of ways to activate
the different rpm limits. The following
steps illustrate a general drag race
installation for use with a Burnout limit,
Launch limit and Race limit.
RAS
ON/OFF
RAS
ON/OFF
Figure 9 Wiring the Start Retard Function.
RAS
ON/OFF
Figure 10 Connecting the Three Step Module Selector.
7AL-3 SIDE VIEW
4500
8
°
7600
5800
4000
Zero
Zer
o
Zer
o
RPM ACTIVATED
SWITCH
HIGH SPEED TIMING RETARD
REV LIMITER
RACE #1
#2
#3
#4
BURNOUT
LAUNCH
Zero
START
Figure 8 Side View of 7 AL-3
START RETARD PLUG-IN
DEGREE MODULE