The pn 8738 is a single rev limit only while the pn 8968 features two rev limits and an rpm activated switch. Some vehicles with factory tachometers may require a tach adapter to operate with the msd.
How To Install An Msd 6a Digital Ignition Module On Your 1979
Msd 6al tach output wire. Gently tighten the nuts in place on the coil. 12 volts and will not work. The tach output wire produces a 12 volt square wave signal with a 225 duty cycle. Tach output wire msd 6al please ber aware the y connector is a good workable solution but if the tach isnt working correctly you might have to add an msd tach adapter to the tach part of the wire feed off the y. There are four wires running from the tach. The ignition will deliver full voltage with a supply of 9 18 volts and will operate with a supply voltage as low as seven volts.
With the new coil in place attach the orange wire to the positive terminal of the coil and the clack wire to the negative terminal. An msd 6al 2 ignition control will operate on any negative ground 12 volt electrical system with a distributor. The msd pn 8738 rev controlor the soft touch engine control pn 8968. Green red yellow and black. The red went to coil and the green went to coil on the old points style ignition but msd says thats a no no with the box. With an aftermarket electric tach the tach signal wire should be hooked to the tach output on the side of the msd box.
Yellow is for the light and black is ground. If it had been hooked anyplace else or there had been a tach adapter used when it was not needed it could have changed the voltage on the msd tach output to approx. Msd 6t 6tn these ignitions feature a special 4 wire connector which plugs directly into an external rev limiter. The msd can be used with 16 volt batteries and can withstand a momentary 24 volts in case of jump starts. Run enough wire to reach the msd ignition control box mounted on the firewall in the engine compartment. The msd ignition features a gray tach output wire that provides a trigger signal for tachometers a shift light or other add on rpm activated devices.
The msd coil has less resistance which is perfect for the msd 6al system. Strip the end of the trigger wire for the tachometer and place a female to female connector to it. Fit new wire from the femalefemale connector and run the wire directly from the spool through an open point on the firewall. Some tachs need the adapter some dont if your tach works right you dont need the adapter simple as that.
Gallery of Msd 6al Tach Output Wire
