Working with a dwell meter

Question:

I bought a dwell/tach meter at a yard sale really cheap. Although I have owned many points-type cars I never used one of these meters! I always used a feeler gauge and a timing light. How does this thing operate? And more importantly, howcanItestittoseeifitworksandis accurate? Are these like some other dedicated purpose meters I have used in other fields and they either work accurately or not at all?

By the way, the car it will be used on is a 1938 La Salle sedan.

Answer:

Normally, a dwell meter has only two leads, a red one and a black one, and is very simple to use. The red lead should be connected to the points side of the coil and the black lead should be connected to a good ground.

Start the engine and with it running the meter should indicate the point dwell. I believe it’s possible for a dwell meter to function but give an inaccurate reading, but don’t really have a bulletproof technique for verifying the accuracy of a meter. I suppose you could adjust point gap with a feeler gauge to get it exactly to factory spec and then measure dwell with the meter and compare the results, with the presumption that the dwell reading will be to the precise factory spec if the meter is, in fact, working correctly.

An easier and perhaps more certain means to proceed with confidence that your dwell meter is accurate is to simply buy a new one. Since they are rather inexpensive to begin with it may be worth buying new rather than used for the added peace of mind.