Be careful- that little circuit board in the tach can IS the tachometer! To my knowlege, no one has had a particular problem with Pertronix, except the usual total failures that all electronic ignitions see. As I remember, MSD wiring can connect two ways, both of which will fire the engine but only one of which will give you all the functions. Go back and reread the intial wiring instructions for the MSD and for the tach adapter, and try Option 2. I don't personally use MSDs so I don't have the info.
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