Early 1950'S Buicks With Brush Protected Generator
This was a protection device designed by Buick engineers to protect the armature inside of the generator from excessive brush wear. When the generator brushes were 80% or more used up the car would fail to start. Buick simply ran the ignition circuit thru the charging system. The Field circuit was used to ground out the ignition circuit preventing the car from starting if the brushes were worn to a point the wire inside of the brush itself could make the contact. Some Buick car owners carried a jumper wire in the glove box to by-pass this circuit in order to drive the car to the dealership for service.
When installing an alternator on a Buick with this "feature" you simply need to find the field wire that is grounded...(found next to the regulator, and is grounded using a sheet metal screw... ground to the body). and connect it to the yellow "exciter" wire coming from the alternator, thus making it a hot wire to complete the ignition circuit.
Fifth Avenue Facts
Even when cars were new back in the 1940’s and 1950’s the vacuum wipers always needed a little help. Because many people smoked during those days, pouch tobacco (like the Bull Durham Brand) was common. During those days it was common practice to rub the tobacco pouch across the outside of the windshield. The "juice" in the tobacco acted as a lubricant that made the job the vacuum powered windshield motor had to do a little easier. The "juice" also made it easier to get the bugs off of the windshield. This is the job that products like "Rain-X" do today.