[FWDLK] I'm positive it's supposed to be negative.

When I received my 1955 Chrysler C-300, someone had accidentally reversed the polarity to negative ground. Easy enough to do if one assumes EVERYTHING is negative ground. It worked ok, except the ammeter read backwards—indicating discharge when charging and vice-versa. If your ammeter is showing the correct indications, someone has done a pretty thorough job of converting the system. My radio did not work then or now, but I suspect the vibrator may be polarity sensitive. (Anyone have directions on how to remove it for service?) I reversed the polarity to factory-spec and shortly thereafter had capacitor failure in the distributor. That may have been a coincidence.

As I recall, Chrysler and GM engineers had a basic disagreement on which polarity gave the longer spark plug life. The thought being that it may be better to force the spark to jump from the rim to the tip to minimize metal loss. Similarly, there was and continues some disagreement on which side of the car was/is safest for a gas tank filler.

The 8-Volt system should not impact the polarity issue unless the 8-Volt battery has the connecting posts in the wrong corners, making cable connections difficult. Most light bulbs were rated at 6-8 Volt.

In the ‘50’s, I saw a lot of Buicks, Packards, Pontiacs, Chryslers and other straight-8 cars with 8-Volt systems in Iowa. 6-Volt systems just did not cut it when the temperature dropped below zero. The ’46 Dodge Power Wagon at the service station where I worked was always busy jump-starting whole neighborhoods on sub-zero mornings. They would wave me down as I drove by. Had to watch polarity carefully, otherwise HUGE sparks from the jumper cables. My ’50 Windsor always started with 20W oil in the crankcase and parked outside.

12-Volt batteries guaranteed nothing. Since they were about the same size and had twice as many partitions, the standard batteries that came in new cars had pretty low storage capacity—and were pretty crappy quality. A new battery every fall was the norm. Charging systems seldom worked just right and ended up overcharging or undercharging a battery. It was soon possible to get HD batteries but the Sears DieHard did not come out until 1967.

Rich Barber

Brentwood, CA (Not missing those sub-zero mornings).

Date: Mon, 9 Apr 2007 08:51:10 -0400

From: Tommy Taylor <ttaylor530@xxxxxxxxxxxxxx>

Subject: Positive vs. negative ground

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I have two 1955 Dodges with one being a Coronet and the other a Custom Royal

(recently acquired). The Coronet has a positive ground 6 V system. The

Custom Royal has an 8 V battery and the positive cable goes to the solenoid and the negative cable to the engine block. This is the exact opposite of my Coronet. The Custom Royal spins the motor over faster when starting and everything works fine on both cars. Can someone help me understand what has happened here? I know people used to put 8V batteries in the 6V cars and tweak the regulator some but the differences in grounds throws me off here.

Tom Taylor