Tachometer question

What do you mean "green to ignition box?" WHAT ignition box? WHAT WIRE on the ignition box?

If you have "switched" coil ignition such as points, HEI, ready to run, Mopar factory, etc, you hook the tach green (trigger) to the coil NEG

If you have an MSD box you DO NOT hook to the coil, and you MAY NEED a tach adapter.

Some tachs (some Autometer) do stop where they "were last" that is if the thing was idling at 900 when you shut it off, they may stay there