Reply To: Connecting rev counter to 1964 3hp Johnson question

[frankr]

You will see two black wires coming out from the under of the 40hp magneto.  They serve other purposes on the 40, among them the ignition switch.  They come from the breaker points in the magneto.  The tach transmitter connects to them, likely at the ignition switch.  Bottom line is, your 3hp does not have those wires and you will have to install one to pick up the signal.  As said, it will be connected to the points exactly like the 40 hp.