pre61-list-digest Wednesday, August 12 1998 Volume 02 : Number 223

Ford Truck Enthusiasts - 1960 and Older trucks and vans
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In this issue:

Re: FTE Pre61 - Positive Ground Battery
FTE Pre61 - Re:12 volt conversion



Date: Tue, 11 Aug 1998 08:16:43 -0400
From: Thomas Teixeira
Subject: Re: FTE Pre61 - Positive Ground Battery

At 8:49 PM +0000 8/10/98, Gary Vandergrift wrote:
>"I have never seen anyone do anything to modify a flathead starter for 12
>volts. They seem to work forever as long as you don't overcrank. More
>fear of destroying the ring gear on the flywheel."
>doing a 12 conversion to my '37. The above statement has raised some
>If I add an alternator and 12V battery, and the 12 to 6V regulator from an
>earlier thread, Do I have to keep the ground on the PLUS side?

You can't have negative ground for the 12V and positive ground for the 6V
(at least not with the simple regulator written about here).

>Most 12V
>systems are Negative ground and if I convert from 6V Positive ground will
>starter run backwards or do I make the 12V system Positive ground?

Since there aren't permanent magnets in the starter motor, when you reverse
the polarity you change both the armature and the field windings and it
does not spin backwards.

>Connect gauges to the 6V regulator.
>Replace lamps to 12V.
>Do I have to change the coil?

You will have to swap the positive and negative wires on the coil. My truck
already had a new coil and an adaptor plate on the distributor. You will
need an ignition ballast resistor.

>Leave starter alone (maybe I put it in upside down to compensate for the
> polarity change).

Yes, you can leave it alone.

>Seems like the question about the starter going backwards would also apply
>to the heater fan motor (one of the things to add in CT), and windshield
>motor (already electric... wait - it goes back and forth... maybe I don't
>care if it is going

Well, my '35 didn't have a heater fan, so I didn't run into this problem.
If the fan motor has two leads, it's easy to reverse them to get the proper
direction change. You will care which way the fan turns unless you want to
suck air out of the cab :-) I don't know if it will hurt the gears any in
the wiper motor to run it backwards, but again, if you have two wires for
the wiper motor, you can reverse. If either of these motors grounds through
the chassis, it will turn backward when you change from positive ground to
negative ground unless you change the wiring inside the motor.

>Are these valid concerns? Is there a book or web site on the subject?
>Thanks Gary V.

Tom Teixeira
94 Taurus SHO 5-speed NESHOC/SHO Registry
'66 Mustang convertible (200 cid auto)
'35 Ford Pickup (flathead V8)

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Date: Tue, 11 Aug 1998 12:45:08 -0700
From: Ed
Subject: FTE Pre61 - Re:12 volt conversion

The starter works fine as is, the rotation is not dependent on polarity.

The gauges will work on 12 volts, won't last. Best to run off a 12v to
6v converter. (someone on the site has posted instructions for a solid
state converter)

A 6v coil will get hot unless you drop the voltage to it. Simpler to use
a 12 volt.

The only difference a change in polarity makes is that the ammeter will
be backwards. On the ones I've worked on the ammeter is run by the main
feed wire from the generator/alternator to the battery, run thru a loop
on the back of the ammeter. To read correctly you have to rerun the wire
in the opposite direction. (this wire can be a fire hazard, a short can
feed the entire battery thru it) On 12 volts the ammeter will have only
half the amperage of 6v so the ammeter may seem to read low.

I can't say about the heater motor. Easy enough to check rotation. The
heater fan speed control is just a dropping resistor in the first place.

?Where in CT?

Ed Sedgwick (Deep River,CT)
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End of pre61-list-digest V2 #223

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