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MSD ignition / tach adapter wiring question...

277 Views 3 Replies 3 Participants Last post by  kevin69
1969 Mach 1 428 with stock tach. I'm running an MSD 6A, and am in the process of installing an 8920 Tach Adapter. When I got the car, the small red wire from the ignition box was connected to the wire that originally connected to the positive side of the coil for switched 12V power. When installing the Tach Adapter, the red wire from the Tach Adapter is supposed to connect to this same red wire, since it is also the trigger wire for the tach. My question is, can I connect both the small red wire from the ignition box and the red wire from the Tach Adapter to the trigger wire for the tach? Or do I need to connect the red wire from the Tach Adapter to the trigger wire, and the small red wire from the ignition box to a different 12v switched circuit?

Just trying to avoid frying my tach.

Thanks -
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I had my '69 factory tach modified to work like a standard tach, which avoids the impact of it being directly inline in the ignition circuit and avoids the need for an 8920.
 
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