There is a simple way to get the 12 volt meter to work on the 6 volt ignition system. It requires a battery from a motorcycle, dry cell from a light, whatever has 12 volts.
Connect the power wires from the tach/dwell to the 12 volt battery, then, add a ground wire from the 12 volt battery to the engine, and connect the sensor wire form the meter to the negative post on the coil. read dwell/rpms, set accordingly.
The power supply from the 12 volt battery will NOT interface/interfere with the 6 volt system. The ground wire from the 12 volt battery to the engine proper only completes the READ circuit on the meter, the two different voltage systems remain separated.
Dwell meter/tach reads correctly when connected in this method.
