I had replaced the coupe gauges with factory SS gauges . What is the proper way to wire the tach ? 1970 chevelle Thanks for any help on this matter...

What kind of ignition are you using? With a factory points ignition, tach wire went to coil -.

I asume you also replaced the under dash harness?
If so the tach wire is a brown wire that breaks out of the harness by itself and runs through a hole in the firewall (should be a grommet around the wire). If you have points goes to coil -. If HEI put a terminal on it a run it to the Tach terminal.

Steve thanks for the quick reply. I forgot to say I'am using a MSD ignition Wayne..

Steve thanks for the quick reply. I forgot to say I'am using a MSD ignition and yes I replaced the dash harness Wayne..

Steve thanks for the quick reply. I forgot to say I'am using a MSD ignition Wayne..

What kind of MSD. If using a 6al box, tach wire must be wired to tach terminal at box and not at coil, as with a box, the voltage at the coil is much higher and can kill a tach in short order.

Greg, Okay thanks. It is a MSD 6 box. I know the clip coming out the side for hooking up a tach and that is where the tach wire goes and not to the negative side of the coil. Wayne

The factory tach may not work right with the MSD. If it doesn't you will have to buy a tach filter.