Interesting, but when you blocked one set of points which one was it and did you change timing? Or leave alone. For DP approaching firing a cylinder, Point Set A open first but nothing happens because set B is still closed. When B opens the coil fires and this is where timing was set. While B is still open A now closes and starts charging the Coil. Then B closes. Hence point B opens to fires the coil, and Point A closes to charges the coil. They share the load of switching the coil. If you blocked B and ran off the A point, you basically retarded timing. Since you started with 20, the motor may have liked that better. OF course this doesn't really explain why a new coil resolved everything, unless you had some intermittent issue.
On the other hand I guess it may be possible that the coil when charging got to point where it shorted and you lost your voltage charge when the dwell was higher, but doesn't do it with lower dwell. Maybe running on single point after sufficient time that coil would start acting up again.
No, I did not change timing. The same thing happened when I blocked EITHER set of points. Yes, the timing does change with one set of points blocked, but not enough to cause the change, i.e. with both sets of points the car won't run above idle, and either set isolated it runs perfectly fine.
