[Carnut427]

The advantage to dual points was the increased dwell angle, giving a hotter spark. Standard single points were set around 30*. What good would dual points do you if the total dwell was also only 30*? None, obviously. If you set your single points at 33* dwell, they wouldn't last long. And yes, when setting dual points, you set one set of points at a time, by putting a piece of cardboard or whatever in the second set, making them non-functional.