Red lead goes to the coil (-) terminal, black to ground. Adjust the point gap closer for higher dwell, wider for a shorter dwell reading. Actually, a dwell meter is just a voltmeter which reads the average voltage between points open and closed. With the points open, you'll see full battery voltage, and zero when they're closed. The longer they stay closed, the lower the average voltage will be. The meter is calibrated to read 60 degrees with the points closed all the time on a 6-cylinder, 1/6 of the 360-degree full turn of the distributor cam. On a V-8, the points-closed reading will be 45 degrees. Best coil saturation happens at about 66% dwell, 30 degrees on a V-8, or about 40 degrees on a 6.

Edit: Always carry a spare set of points and condenser, and a screwdriver in the glove box! You can do a field setting on point gap with a matchbook cover or a business card to get you running in an emergency!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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