Tachometer Hook Up

[BP57CUSTOM]

I have an original 9m  rpm  Cobra tachometer that I may want to put on my 57 with 312 engine with the resistor mounted next to the coil. I think this is a series type tach. it has 3 wires 1 red ,1 black and 1 blue. I know the blue is for the light. Do I just splice into the wire going to the + side of the coil and attach the black to one end of this wire and the red to the other end? I welcome your advise if you have done this.
Thanks

[Ford Blue blood]

Barry you are going to need power to run that tach.  If I were a betting man my educated guess would be the red is +12V run, black is ground and the blue goes to the distributor side of the coil.  Might be there is a missing wire?  I just know that the tach needs power and a signal from the ignition.  It has trons inside that take the signal from the points and turns it into current flow to move the needle.

Might try googleing that thing and see.

[BP57CUSTOM]

Thanks , I think I will do some googleing before I try hooking it up. This is quite valuable now and I don't want to fry it. You have a good day.
Barry

[canadian_ranchero]

the factory mid 60's mustang tachometers were hooked between the ignition switch and the power wire running to the coil

[BP57CUSTOM]

Yeah , I had this on a 65 mustang and on a 56 f100 many years ago but had forgotten how I did it. I must be getting old.