12 volt system.

S

swoopNZ

MEMBER EMERITUS
A friend wants to convert the headlights on his 39 coupe to 12 volt.
What should he have to do regards the interior lighting - dash, clock, tail lights and rear license plate bulb.
Also the horn ?
Thanks in advance.
Chris. NZ.
 
I know you're not going to like to hear this, but tell him to buy an Optima battery and clean all of the connections and make sure the battery cables are big enough.
 
He will need the little 12v-6v resistor things for EACH of the original 6 volt instruments. Not sure about the radio, it will probably need a big voltage drop thingie.
 
swoopNZ said:
A friend wants to convert the headlights on his 39 coupe to 12 volt.
What should he have to do regards the interior lighting - dash, clock, tail lights and rear license plate bulb.
Also the horn ?
Thanks in advance.
Chris. NZ.
Click to expand...

All of the bulbs need to be changed to 12v. The dash gauges etc, need a voltage reducer. The horn will work on 12v but not as well as it did on 6v. :)

There are a lot of articles on the details of switching. You can run the original 6v starter, but the Bendix will hit a lot harder. The starter solenoid may have to be replaced and the starter button change from a ground source to a positive source. Going to have to do something about the generator. Depending on the coil you will have to add a ballast resistor or replace the coil. And remember you are reversing the polarity, so the coil will need to be wired to match the polarity.
 
If the power rating is the same, 6 volt headlamps should be just as bright as 12 volt headlamps. Why bother changing? Jack E/NJ
 
Chris, in addition to the usual advice regarding cleaning up the electrical connections including grounds, installing an Optima, and using headlight relays up near the lights, the lens itself needs to be removed to the kitchen sink and with hot water, dish detergent and a non-metallic scrubber, get off all those many years of smog stains from the inside of the lens. Lots of guys are surprised to learn that those lenses were originally bright clear glass, not dull yellow!
 
Yep just done my 39 coupe full conversion to 12v, power gen alternator, halogen h/l bulbs all other bulbs 12v, dropper for the gauges, 12v coil with ballast etc and Ive installed a 60amp thermal fuse for safety off the solenoid make sure cables are up to it with good clean earth horn starter etc leave alone. Works a treat so far.
 
Phil Gillespie said:
Chris, I've brought a 6 V Optima off Trade Me, some outfit in Auckland has them.
Phil NZ
Click to expand...

So did I Also brought a dummy case off Ebay for it to sit in. Looks stock but many times better than what I had before -I have 6v Halogen bulbs and very bright lights. The only advantage I can see for 12V is that when you are on tour you can source a bulb from just about anywhere if you are running 12V not so easy on 6V -Karl
 
A few hints which helped 12v conversion of my 50 Merc:



  • Starter - Buy 1964 Galaxie starter, O'Reilly's $55, use its housing and 12v field and keep the existing 6v armature and bendix. This gives slower start speed and reduced bendix slamming, provides best of both world's.
  • Heater motor fan - Autozone VDO PM394 $29 - choose amungst any of 4 speeds, choose cw or ccw, cut shaft length as needed, 5/16" diameter.
  • Gauge regulator - on eBay buy a used early Mustang gauge regulator for about $15. Mustangs use 6v fuel oil temp instrumentation using a proper Ford gauge regulator.
  • Radio - I will publish the proper conversion soon. I spent about $60 using tubes, no dropping resistors.
  • Halogen headlights require relays otherwise the high beam indicator doesn't work right.

Forgive my non-familiarity with the vagarities of 1939 Coupes nor NZ stores but these 12v conversion hints are not as common as they should be.
 
deuce lover said:
Distributor & Coil ?
Click to expand...

Distributor is not an issue, the coil is. The coil has to be a 12v coil OR have a proper ballast resistor installed. You want around 3.0 ohms resistance, so a 3.0 coil OR a 1.5 ohm coil and a 1.5 ohm ballast resistor.
 
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