10
INSTALLATION INSTRUCTIONS
M S D I G N I T I O N
• w w w . m s d i g n i t i o n . c o m • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • FA X ( 9 1 5 ) 8 5 7 - 3 3 4 4
2. Connect the brown/Orange wire from the RET-2 terminal to the 12 volt source side of the number
two nitrous solenoid. When the second solenoid is activated the ground is removed and the RET-2
module is activated.
note:
Since the number one solenoid remains on, the first and second retard modules are now
activated and their retard amounts are added together.
3. To activate RET-3, the brown/Green wire is connected from the RET-3 terminal to a normally closed
(N.C.) microswitch on the shifter. When the shifter is pulled into high gear, the switch removes the
wire from ground which activates the third retard. The total sum of the three retard amounts are
now activated.
4. Since RET-4 is not being used, a "zero" degree module must be installed, or the terminal must be
grounded.
Figure 13 Connecting a Tachometer.
tAcHoMeteR
This terminal provides a square wave 12 volt, 20% duty
cycle signal for your tachometer. Use the supplied brown
wire and connect it to the Tach terminal strip (Figure 13). If
your tachometer reads erratic or does not operate properly,
a Tach Adaptor may be required. If you are using the white
wire to trigger (points input) you will need Adapter PN 8910.
If you are using the magnetic pickup, PN 8920 will be the
right Adapter. Contact your MSD dealer.
RetARD WItH tHe RPM ActIvAteD SWItcH
The MSD 7AL-3 has both an RPM Activated Switch (RAS) and a Multi-Step Retard. The stages of
retard are activated when the corresponding activation wire is
removed
from ground. The RAS can
only activate a circuit by
providing a ground path
.
If you want to use the RAS to activate a retard stage of the 7AL-3, an external relay must be used. The
MSD Relay, PN 8961, is supplied in the parts bag with the 7AL-3. Figure 12 shows how to connect the
relay for this application. RET 1 is grounded through terminals 30 and 87A of the Relay while the relay
is off. Terminal 86 receives 12 volts from the ignition terminal and when the desired rpm is activated,
a ground path is supplied to terminal 85 which turns the relay On, activating the retard.
note:
Make sure 12 volts is applied to the RAS On/Off terminal.
NOTE: THE RELAY IS SHOWN
IN THE DE-ENERGIZED
POSITION.
Figure 12 Using the RAS to Activate a Retard.
