[antiquepa]

WHAT IF ANY, WAS THE REASON THAT THE 6 VOLT BATTERY WAS POSITIVE GROUND, THEN LATER CHANGED TO NEG. GROUND/ DOES ANY ONE KNOW, IT WAS JUST A QUESTION THAT COME UP AT MC DONALDS WHILE A BUNCH OF RETIRES WERE DRINKING THERE COFFEE. DOES ANY ONE KNOW.

[Rusty_OToole]

If you look at your battery the positive post always corrodes more than the negative side. They figured, if your cable is going to rot off it is cheaper to replace a 1 foot long ground strap.

Other than that I don't know any difference. Have wondered why they went to neg ground myself.

[BillP]

2 reasons as I understand it:

It was found that body corrosion was greater with + ground. In the mid-thirties most makers had gone to all steel bodies and corrosion due to electrolysis became more evident. I don't know how the steel would care which way current flowed (flew?), but apparently so.

It was also found that if the spark came off the center electrode and went to the lug, it made a spark of greater intensity. I believe the thinking is that the center electrode is hotter relative to the lug (lug is in contact with the cooled cylinder head) and thus has more energy. The electrons comprising the spark fly off the electrode more readily.

The effect then of connecting your coil backwards is to cut spark strength roughly in half, no way to win the race.

Being naturally sceptical, I guess it may have been none of this. Maybe the guys with sharp pencils figured they could save a nickel a car by switching the terminals and merely called the change beneficial to the motorist. I goofed one time and hooked up the Packard backwards, drove up and down the driveway and if I recall correctly, even played the radio. But I don't know.

[Mark Shaw]

I agree with the electrolysis theory. It simply makes more sense.

[Twitch]

This is the way I heard it- Ford was the first automaker to do this and for good reason. Due to gasses from the battery, the positive terminal always has a tendency to collect corrosion and cause poor connection. Ford engineers thought if the applied the positive terminal of the battery to the ground connection (reversing current flow) it would reduce the terminal corrosion and the corrosion that would form would not have as much effect on reduced voltage. When connecting a battery charger to a positive ground car always connect the charger (+) red lead to the Battery (+) side.

[Restorer32]

You always connect the + lead of the charger to the positive battery terminal regardless of how the battery is grounded !