How to Hook Up a Tach Dwell Meterby Robert Bayly
A tach-dwell meter is a combination electronic device that measures engine rpm as a tachometer and ignition point dwell angle. The tachometer function is self-explanatory; it measures engine speed in revolutions per minute. The dwell function measures the degrees of distributor rotation that ignition points are closed and is directly related to ignition point gap. In fact, the ignition point gap can be set by adjusting the dwell angle.
Attach the red lead on your meter to the negative "-" terminal on the ignition coil.
Attach the black lead on your meter to any good ground on the engine; that is, an unpainted metal part.
Set the meter for the number of cylinders your engine has. There should be a switch with engine settings on it.
Set the meter for "tach" or "dwell." The meter will have a switch for this. When using the meter, switch back and forth between tach and dwell.