HI, I have a '70 tach I'm trying to wire with 2 posts jumpered together and a long green wire off one post (assume that goes to (-) coil?). It looks like it's grounded to chassis, but I don't see a 12V lead or anything. Doesn't it need to connect to power? I do see a short grey wire, but looks like that's for lighting..?.?

 

Welcome to Classic Olds!

This thread should tell you everything you need to know about wiring your tach:
https://classicoldsmobile.com/forums...up-messes.html

This post, in particular...
https://classicoldsmobile.com/forums...tml#post145636

If not, just let us know!