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Re: [Mgs] positive ground

Subject: Re: [Mgs] positive ground
From: Bob Howard <>
Date: Mon, 20 Apr 2009 10:32:53 -0400
    These cars are not particularly polarity sensitive.  Lights are not
affected, clock and wiper don't care. Ammeter works OK either way, but
will show incorrect reading if polarity reversed. Dynamo should be
polarised to whatever system you want to have.
    Does the ground cable connect -- on the battery to the battery box? 
If yes, it's now  connected asNeg earth.
    If it is neg earth and the ammeter shows charge when engine revs up,
then someone has already converted to neg earth.
    If the ammeter shows increasing discharge as engine revs up, car is
still Pos earth and battery is connected backwards so you can turn it
    There is a polarity for coils.  Originally, when pos earth, the CB
terminal of coil went to Contact Breaker (points) terminal. Replacement
coils are usually + and -.  Someone will know for sure which way to
   If the polarity of the dynamo is uncertain, just "flash" it.  That
will not change polarity if it's what you want or will reverse polarity
for you. 
    If you keep it Pos earth, you can install a cigarette lighter that is
wired pos to the center post and neg to the shell that will power CB and
anything else you might want that needs neg earth, and you can make up an
electrical bridge of diodes to use in the little dash panel sockets that
will ensure that the polarity is correct for the device you want to power
from them.

On Mon, 20 Apr 2009 06:36:44 -0500 "oliver" <>
> just picked up a 52 td last week.
> sat in a garage 30  years.  the dpo put a battery in it, and this 
> weekend we  got it running.
> am a little concerned, tho, because the battery is in standard 
> position, and  the car should be positive ground.
> is there a way to tell if it was ever converted to negative ground?
> would it start and run if the battery was in backwards?
> what should i do at this point?
> i wouldn't mind having it positive ground.
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