Hello everyone, Question, I have an old Autometer tach from the 60’s (I believe based on markings inside) that I’ve decided to try and use in my car. My intent was to stay period correct if possible. It is a two-wire tach that puzzles me a little. It has a (+) and (-) terminal on the back of the tach. Two other studs for mounting. An Autometer sender, model 84V, is mounted to the back and terminated at the (+) and (-) terminals on the tach. On the sender it has a terminal called ‘Dist Pri’ for the signal and a terminal for ‘grd’ Or ground. So I wired the ground to my grounding lug on the engine block. This ties directly to the ground terminal on the battery. My car came with a Summit ‘Ready to Run’ billet distributor and Summit coil. The distributor had a three wire harness—-ground which is tied to the block, red wire which terminates at the coil + and an orange wire to the coil negative terminal. I tied the ‘dist pri’ of the tach to the negative side of the coil with the orange wire from the distributor. When I turn the key, I see the needle on the tach go to zero. Starting the car it appears to show the proper RPM level at idle (650 RPM or so). Then the needle just gradually climbs and goes as high as 5000 RPM. Again the engine is still idling. Turn the car off, it goes to zero. Start the engine, the same occurs. Anybody ever seen this occur? It could be the sender or perhaps I just use this old tach with this style dizzy? Just wondering if you all have any advice. I have two of these tacos and they’re really a nice period correct addition. Perhaps I can have a more modern movement put in this unit?