I used std atd with two sets of points on my norvin for several years but it wouldn't tick over properly or shut down quickly when the throttle was closed.Eventually realised the atd is set up to overcome the drag of a mag whereas points don't really have any drag so it wasn't retarding!.Now running a fixed mag pinnion with a harley atd (which by the way is a real quality piece of kit being properly machined out of steel not pressed from tin) with one cam ground off and the same twin points.Starts first prod,ticks over,pulls from nothing and shuts off instantly even running 34mm mikuni's and MK11's