Pushbutton Start Dislexia ??????

"I" = Ignition

"S" = Start

The "I" terminal is connected to a small auxilliary contact that provides a direct 12-volt source to bypass the resistor in your ignition circuit when the solenoid is energized.

A usefull choice would be a solenoid designed for dual battery camper applications. These have the coil wires connected inividually, and directly, to the small studs, and could be connected as described by Randall.

The original Ford solenoid had one side of the coil winding connected internally to the BATT post on the solenoid, and the other one was connected to the START terminal on the solenoid. When the start button on the transmission cover was activated, it completed the circuit from the solenoid coil to CHASSIS GROUND (Plus side of battery) and the solenoid pulled in, completing the high curent circuit to the battery.

Most modern 12 volt starter solenoids have one side of the coil connected to the mounting leg of the solenoid (Chassis ground), and therefore, require 12 volts from a starter switch to be applied to the START terminal on the solenoid to cause the solenoid to pull in.

The difference is NOT that positive or negative ground is used. The difference is in the internal circuitry of the solenoids.

There are certain 12 volt solenoids available that can be used with the existing starter switch on the "N"s, thereby preserving the neutral-start safety feature of the original switch on the transmission cover. Drop me an email, if you need sources and numbers.

who sez: everything you say is true BUT really doesn't answer the original question

But by your logic, you should also change the starter to 12 volts. Which negates the 12 volt advantage of spinning the 6 volt starter faster for quicker and eazier starts.

As I pointed out, the original question had to do with effect of battery polarity on solenoid operation. Solenoid don't care, postive or negative ground works just fine, just like the starter doesn't care, positive or negative ground, still spins the same direction..... ..... respectfully, Dell

The coil will produce a magnetic field regardless of the direction of current flow. The contacts will close regardless of the orientation of the magnetic field.

The electron flow and magnetic field orientation in your solenoid will be reversed when you make ground negative and the big post positive, but the contacts will still close when you energise it.

Think of a horseshoe magnet. One "prong" is "magnetic north", the other prong is "magnetic south". But either one will pick up nails.