Trying to install my new solid state tach and things are not going too well. Red wire goes to keyed voltage from the fuse block. Black jumper goes direct to - battery post. Green has gone to the - coil, + coil and the gray/black lead from the MP orange box. Every time i get 2000rpms with the key on and the tach reads backwards when the motor is running. Any ideas? I read one post about switching the polarity by flipping the leads out of the distributor and no luck.

MP orange box and distributor. Solid state voltage regulator, stock ballast resistor, coil.

More info, How is the tach reading backwards? Might power the tach hot lead directly to the batt positive post (or starter relay batt stud) just for a test. On the dist leads, the eng (timing) runs good except for the tach issue?). I would check/clean all (related) connections for starters.

got a pic of the tach wiring diagram?????

model????

your green/black don't seem right.

Went direct to battery power and no change. When I say it runs backwards it moves to zero when I accelerate. I wired in another tach I had lying around the shop and it works. so I think the old Electro-tach with new solid state internals does not like my ignition set up. I've read I could try a tach adjuster but that does not make sense to me. I think I will return this tach an look for another one that will work.

Maybe I'm forgetting something... Seems like RED goes to +positive(power source).. BLACK to negative side of coil... and GREEN to ground

Just checked and your right.. but not sure why/what the problem is.

52 savoy, you have the black and green backwards. Red -keyed hot, black- ground, green - coil negative or signal source if using an MSD etc. white (or yellow)- light. That is the standard wiring for tachometers

I think I was wiring it for 120v..

That would make for a very bright shift light.

Returned the tach. Seems the new board does not like the orange box ignition set up. Too bad it was a nice period correct tach for my car.