Yeah, disconnecting the battery will send the alternators voltage regulator into overdrive, putting way too much voltage/current into the system.

Kelly's comment on distributor teeth wearing brings up some good info. Most older motors run the distributor off of the cam shaft through a gear (to which Kelly is referring).  The distributor shaft also runs the oil pump so the biggest load on that distributor gear is the pump. Lots of force, especially if you install a HV pump or tighten up the pressure regulator.