rlofaro

Hi Everyone,
I have a question about the tach hook up for HEI ignition.
I have an HEI distributor in place that was installed by the previous owner. I want to connect the tach output from it to the factory tach.
I have the wire diagrams for the car, but I do not see the original wire connector to drive the tach in the harness.
So I would like to run a wire from the tach connector on the distributor to the tach. Can someone tell me what connector out of the 3 connectors on the back of the Tach, that I would need to connect this wire to?
The casing of the tach will have ground provided, and I am not sure if the 2 other connectors that are left blank when I do connect the tach wire need something else connected to them such as a ground.
This is a 1973 vette.
Thanks so much!
Richie

tigers123

If this is a 1973 corvette, it came with a mechanichal tachometer and cannot be wired to the distributor. However if you are saying the tachometer has been replaced with a 1975 or later, the wiring for the terminals is shown on the printed circuit board on the tach. It is a 3 wire hook up for the 1975 tach. One terminal is ground, one is 12 volts, and one is for the lead or terminal on the Hei distributor. They are marked on the circuit board. To see this however you need to remove the tach from its housing. Simple spade terminals and three different colored wires will help you if you make you a little wiring schematic and write it down so that you can tell later which wire goes where.

rlofaro

Thank you very much for the info. Yes it has been replaced with a 1975 tach.
I appreciate your help.
Richie