Converting from 6 to 12 Volts
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Continued
General Applications
As stated earlier, the Amp meter will work
just fine and read correctly on 12 volts. The fuel gauge will need to have a dropping
resistor attached between the positive terminal and the positive wire supply power to the
gauge. This type of dropping resistor is available from most of the classic truck parts
suppliers for about $10.00. Do not use the large load dropping resistor.
You will need to
run a fan and wiper motors. As most older trucks use mechanical oil senders,
so there is
nothing to do here.
Next, all the instrument light bulbs need
to be changed to 12 volt. If you forget this part, you will be reminded one night in a
bright flash and drive home in the dark.
Don’t for get the radio if you have
one. The best way to handle to power requirements for a 6 volt radio, would be to contact
your local automotive radio repair shop. I know that operating a 6 volt, tube type radio
off a dropping resistor is bad news. Supply wire sizes also are factors to take into
consideration. This is an area best left up to the experts, if you can find one.
Heater and Wiper motors will need a heavy
load, ceramic dropping resistor. Mount the resistor in the engine area, as it emits a lot
of heat. Buy a good one, big, with a good ceramic heat sink. Any NAPA dealer can supply
this item as well as many of the vintage truck parts suppliers for around $45.00. The part
is made by Echlin and the part number is BT-6187. Tie all your motor loads to this
resistor and use the proper size wire for the loads you are running. If you can handle the
expense, you may want to replace the old heater and wiper motors with new 12 volt models.
Replacement of these motors will save you time and the need to rewire.
Positive ground
trucks link GMC and Ford with require an inverter to properly power
the instruments. You can inverters large enough to run
everything you want to keep positive grounded. Inverters are usually
cost less than converting instruments to negative grounding and
replacing radios and wiper motors with negative ground units..
STARTING SYSTEM
This part is probably the easiest. If you
have a starting solenoid for your starter, change it to 12 volts. The 6 volt starter will
work fine on 12 volts, sometimes better. It is hard sometimes to find 12 volt starters for
older trucks, so if you have to replace a worn starter, there is no problem with using an
original 6 volt starter.
Positive ground starters present problems
in some cases. If you cannot find a negative ground starter that will fit your application,
you may need to seek out a good auto electrical repair shop to have the motor leads
reversed. You can do this your self, but if you are not confident in your work, seek
professional help.
You will need to add a ceramic ballast
resister to your 6 volt ignition coil. A firewall mounted resistor, such as thoughts use
on early 12 volt GM products are the easiest. These resistors are available from Napa Auto
Parts for about $10.00.( Napa Part Echlin ICR-13) The resistor is installed inline on the
12 volts supply to the distributor dropping the ignition to 6 volts.
LIGHTING SYSTEM
This area too, is pretty straight forward
and is really here just as a reminder. Remember to change your Headlamps, Map, Courtesy,
Brake, Turning and Parking lamps. One thing I really like to do when going 12 volts, is to
use Halogen Headlight lamps and bright bulbs in the Brake & Turning lamps. Original
Brake and Turning lamps are usually pretty small as far as today’s standards are
concerned and bright bulbs really help you be seen at night. Halogen Headlights will also
greatly improve your night vision and get rid of that old yellow look associated with
older vehicles. CTS
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