It's possible to use an old-fashioned analog voltmeter (the one with the needle, not digital) as a dwell meter. When the points are open, the meter will read applied voltage, the same as is coming to the coil. "Points closed" will read zero volts, or a tiny fraction of a volt if the points are a little dirty. It's pretty simple to figure out the voltage that will be indicated for a particular percentage of "points closed" time, and convert that to a "degrees of dwell" reading. Since most distributors work best at about a 66% "points closed" time, adjust the point gap to read about 1/3 of applied voltage to the coil with the engine idling.
Jerry
