[alexiskai]

That's my understanding – 4-cyl engines operating at the relatively low RPM range of the Model A get all the dwell the coil needs quite easily. I always understood the advantage of the B distributor cam to be that it reduces wear on the rubbing block. If you look at the '32 service bulletins, "dwell" is never mentioned in the context of the Model B, only when talking about the V8s. In the Model A service bulletins, dwell is never mentioned at all.