Tractor Repair: point gap, cam lobes, point gap

Question
My repair manual indicates the points are to be set at 0.015 with the brush at the low point of the cam.  I thought that the points were to be closed at the low point of the cam.  This is an 8N about 1940.
What is the proper setting on the cam?

Answer
Hello,

  You are correct, the low point is where they would be closed. I don't know why the manual would tell you on the low point of the cam.  The only way you can gap them is with them resting on the highest point of one of the cam lobes where they are being held open.

                      Arnie