[TommyBr]

I have MSD distributor and MSD Blaster Coil without control box in my 1973 350 Nova, it was installed by previous owner.
MSD distributor has only 2 wires black and red so it is version without third wire (tacho signal).
What is the proper way to install tachometer, should I put signal wire from tachometer to positive or negative terminal on MSD Blaster Coil?

 

[Pmotion]

In most cases the tach is connected to the negative side of the coil.