A dweel/tach meter attaches to the plus and minus of the coil.
It can show various items, from point resistance to if your point gap is set right as well as used to set up carburetor idle and mixture screw.
If dwell reads in the right range then the points are adjusted to the right gap. Dwell reflects the period the points are open in degrees.
If you see a dwell reading near the right range while cranking the engine then your coil should be getting the proper pluses it needs to fire.
Some meters do not like 6V systems, I have two old analog units that do not care 6V 12V Neg ground or Pos ground, they work and read correctly. I had a fancy digital multimeter that would read dwell and it did not care (now if I just could find where I put it).
I do not know if any one has tried the HF units to see if they read.
