Msd Tach Adapter Wiring
The pn 8920 will correct the operation of most voltage triggered tachometers that do not work directly off the tach output terminal of the msd control.
Msd tach adapter wiring. Mount the tach adapter in a location away from direct engine heat making sure the wires reach the msd unit and the coil. The auto meter tach adapter wires in line on the positive 12 volt supply wire. This terminal provides a trigger signal for tachometers a shift light or other add on rpm activated devices. To install the tach adapter the coil positive wire must be identified for your application.
The tach output terminal produces a 12 volt square wave signal with a 20 duty cycle. The msd ignition features a tach output terminal on the side of the unit. It is recommended to have a wiring schematic of your vehicle s ignition system to clearly identify the coil positive 12 volt supply. It senses current on the coil positive wire and converts it to a 12 volt signal output.
If the tach still registers incorrectly install this tach adapter. Vehicles originally equipped with a cd ignition control cannot use an msd. Splice the red wire from the pn 8910 into the msd s red switched 12 volts wire. If the tach still registers incorrectly install this tach adapter.
Voltage triggered and current triggered. Once the wire has been located it is recommended to check for 12 volts using a volt meter. Fit new wire from the female female connector and run the wire directly from the spool through an open point on the firewall. There are two style tachometers that may have been used on your vehicle.
The auto meter tach adapter wires in line on the positive 12 volt supply wire. Some vehicles with factory tachometers may require a tach. There are two style tachometers that may have been used on your vehicle. 7 for wiring and tach adapter information.
Voltage triggered and current triggered. A good quality helically wound wire and proper routing are required to get the best performance from your ignition such. Msd tach adapter pn 8920. Run enough wire to reach the msd ignition control box mounted on the firewall in the engine compartment.
If your tachometer doesn t work correctly after installing an msd ignition control always try to connect the tach s trigger wire directly to the tach output of the ignition. We drill a new hole and run the wires through the firewall below the starter solenoid. Spark plugs and wires spark plug wires are very important to the operation of your ignition system. Figure 1 wiring the tach adapter.
If you are using the magnetic pickup input green and violet wires to trigger your msd ignition you will need the pn 8920 tach adapter.