Went to hook up the old auto meter tack on the chevelle and it grounded out the fire and killed the motor. Im almost sure I hooked it up right but maby not so I thought I would ask u guys to be sure. The tack only has three wires one red goes to battery source, and two black wires that are together, solid black to ground, black with writing to tack lead off distribtor. Did I do it right or has the tack just went bad from sitting?

What kind of ignition system? Are you sure you connected the tach lead to the proper place?

Usually there's a green wire that goes to the neg. side of the ignition coil.

Unless you have a "prehistoric" autometer tach....it might different colored wires but should still work the same.

Im running a factory GM hei that has the built in coil in the cap that came out of around a 80 camaro the cap has two conections holes beside each other, one for the hot lead and one for the tack lead.

How old is this tach?............ Have you used it before?

The older tachs used a sending unit, I have an old Sun tach that the gauge head has 3 wires, 1 wire is for the gauge light and the othe 2 (black) wire connect to the sending box.
Remove the gauge head from the case and make sure the 2 black wires where not spliced in to different color original wires. You can always contact AutoMeter on their website and get info about this model tach..... Good luck