Alternators can be installed on Buick cars of the 1940's and 1950's that used a vacuum operated switch to engage the starter. Originally...to start the car you turned on the ignition switch then pushed the gas pedal clear to the floor. This released a vacuum switch and engaged the starter.

A safety feature was present in that after voltage from the generator reached the vacuum switch, the starter could no longer be engaged. When installing an alternator (that has output all the time) here is how to do it.

First, install a remote starter button such as the type used on Fords of the early 1950"s. Next, locate the vacuum switch wire on the ignition switch. Now, connect a 14-gauge wire from the vacuum switch over to the remote starter button, using the vacuum post on the ignition switch. Now run the two wires necessary for the defroster and related accessory to the hot side of the vacuum terminal. If your wiring is correct you will be able to engage the starter only from the remote switch, Meanwhile… tall of the remaining accessories will work as before, that includes any that were powered from the ignition/vacuum switch.

The vacuum switch wire at the relay connects to the solenoid wire at the relay. The relay is now no longer used.

STARTING THE CAR...
Turn on the ignition switch, hold the remote starter button in, and push the gas pedal to the floor just as you did before. When the car starts...release the remote starter button.

The vacuum switch can be by-passed completely by connecting a 14-gauge wire directly from the remote starter button to the starter solenoid. The remote starter button will then start the car but will not work as the original did. If you decide to do this.... the vacuum switch and wiring can be removed completely.