Another measurement that almost requires an analog meter is measuring point dwell. A dwell meter is nothing more or less than a voltmeter, and it measures an average of points open/points closed voltage. With the points closed, the voltage on the downstream side of the coil is virtually zero, since the closed points are at ground potential. The only possible voltage reading would be indicating whatever resistance the slightly dirty points have. The "points open" voltage will be the same as battery voltage, since no current is flowing with the circuit interrupted by the open points. If the dwell is 30 degrees (of a possible 45) on a V8 engine for instance, that means the points are closed 66% of the time. The dwell meter will indicate 0 volts for 2/3 of the time, and battery voltage the other 1/3. With a charging system voltage of 14 volts, the "dwell" voltage at the distributor side of the coil will be about 4.6 volts. Try it sometime (with an analog meter).
Jerry
Last edited by Hotrod Lincoln; 03/05/2014 6:56 PM.
