Soft iron such as the pole shoes for field coils do not retain magnetism very well. Polarizing creates a magnetic field by running current through the field coils, and some of it remains as "residual magnetism" after current stops flowing. Simply jumper battery voltage fron the "Bat" terminal of the regulator to the "Arm" terminal with the wires connected between the generator and the regulator for half a second or so, and the generator is polarized. Some guys short across the terminals with a screwdriver blade, but I prefer a short jumper wire. The most common way polarization is lost is if the generator housing is bumped or handled roughly during installation. A quick way to check for residual magnetism is to spin the generator with the wiring disconnected by running the engine. A polarized generator will develop about 1/2 volt or slightly more at the Armature terminal with no wires connected to it. Grounding the field terminal with the armature turning will cause a very high spike of voltage, up to 40 or 50 volts sometimes.
Jerry
