Your description sounds like a magneto, rather than distributor. A magneto is runs at engine speed, but in a 4 stroke engine, only two cylinders are actually firing on each revolution. Each cyllinder has a compression stroke, and an exhaust stroke, so up to TDC twice. However, the magneto only needs to fire twice in a given engine revolution. So with a firing order 1342 cylinders 1 and 3 fire on one engine revolution, while 4 and 2 fire on the next. So the points need only open twice per revolution. The rotor has twice as many teeth as the pinion, so it requires two rotations of the magneto armature to go fully round once, therefore firing all 4 towers over two engine revolutions. See how it all works out?
Hope this helps in understanding. Also, see if you "distributor" has a rectangular cover on top, where the internal coil should be. That would confirm that you have a magneto. If it is a magneto, the points gap should be set at 0.013" rather than 0.020".
edited because I really screwed this up the first time.......
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