hot rod tach wiring help

have a WICo tach with 3 wires and cannot figure it out 1 is the light where do the others go???

 

What colors are the wires and is there a model # on it at all?

 

red white and black. The red goes straight to the light

 

Black should be your ground and white should go to your coil then.

I'd run a quick test on it to verify the light works using the red and the black.

 

Welcome from South Georgia

 

I have tried white to coil and black to ground touched it and tach jumped past 8 grand then i tried connecting tach between ing side of coil and coil did the same thing Jumped way past 8 grand????

 

What's it out of, could it be that it came out of a positively grounded vehicle?