6v to 12v Conversion 1951 B2

[NJpilot]

hi, new to the forum here!  my dad has a 1951 b2 that we'd like to convert to 12v.  we are looking for help on exactly what we need to replace and a good place to find the parts we will need.  i am just labor, my dad is a very competent mechanic and has kept her running since he bought her in 1965.   would really appreciate whatever knowledge anyone can share.    thank you 

[Merle Coggins]

Welcome to the group.

Just curious as to why you wish to convert to 12v? If it has been well maintained it should function just fine on a 6v system, as designed. What is the condition of the electrical system?

However, to make the conversion you will need a 12v battery, and alternator/generator upgrade. You will also need to replace all of the light bulbs to 12v versions. You will need a ballast resistor in the ignition wire to the coil, and you may also need to reduce the voltage for the fuel level gauge. Since your 12v system will likely be Neg ground you will have to reverse the wires on the Ammeter. And if you have a heater you will need to upgrade the blower motor or find a suitable voltage reducer. The starter will work fine on 12v, or so I've heard, as long as you aren't cranking for long periods of time.

[cavisco1]

You could use one of these and then you would have a great vacuum source for you wipers as well as 12 volts. Requires an oil line to the pump so some fabrication may be required.

http://www.ebay.com/bhp/isuzu-npr-alternator

Edited December 9, 2016 by cavisco1
oil line info

[wayfarer]

9 minutes ago, cavisco1 said:

You could use one of these and then you would have a great vacuum source for you wipers as well as 12 volts. Requires an oil line to the pump so some fabrication may be required.

http://www.ebay.com/bhp/isuzu-npr-alternator

...it says "pump not included".....

[cavisco1]

10 minutes ago, wayfarer said:

...it says "pump not included".....

You may need to look at more than the first one..

[wayfarer]

...only the 'first' one showed up on the computer that I was using this morning so it looked like a direct link to 'that' product.....

[NJpilot]

On 12/9/2016 at 0:42 PM, Merle Coggins said:

Welcome to the group.

Just curious as to why you wish to convert to 12v? If it has been well maintained it should function just fine on a 6v system, as designed. What is the condition of the electrical system?

However, to make the conversion you will need a 12v battery, and alternator/generator upgrade. You will also need to replace all of the light bulbs to 12v versions. You will need a ballast resistor in the ignition wire to the coil, and you may also need to reduce the voltage for the fuel level gauge. Since your 12v system will likely be Neg ground you will have to reverse the wires on the Ammeter. And if you have a heater you will need to upgrade the blower motor or find a suitable voltage reducer. The starter will work fine on 12v, or so I've heard, as long as you aren't cranking for long periods of time.

so the thinking was more cranking power for starting, brighter headlights, and in general just  a more modern system.  i though this would also help with an issue of the engine not wanting to start after iv'e used it in warmer temps.   if i don't open the hood and let it cool for 20-30 minutes after i've used it for a bit when outside temps are in the 60s or higher, it will just crank until the battery dies without catching.   engine temp remains 190 or so whenever i use it, just the issue of shutting off and restarting without a "cooling off" period.    

 

 we've since changed our minds and are leaving it be, for now.  thanks for the responses.  this will be good to have for future reference.     

[Don Coatney]

If charging is an issue you can convert to a 6 volt positive ground alternator. However it appears your biggest issue is hard starting when hot. Couple of things to look at. The alcohol enriched gasoline sold these days has a rapid expansion when the engines saturated heat rises when the engine is shut off. When this happens you are most likely flooding the intake manifold with raw gasoline. Suggest you lower the float level in the carburetor to prevent flooding. Also your coil may be failing. If the coil is too hot to touch try using a damp rag or an ice cube to cool it.

Do not grind the starter for long intervals until the battery fails. Try using short 6-7 second bursts with a resting period of 10 or so seconds in between. A hot starter motor draws more amps and drains the battery quicker.

 

[Merle Coggins]

A 12 volt upgrade won't necessarily improve the brightness of the headlights, and such. Good 6v lamps with proper size wire, and quality grounds can be just as bright. I have driven mine at night and have no issues with the amount of light from the headlights, which are 65+ years old. Also, be sure you have good heavy duty battery cables. If they are too small you can't push enough current to the starter for proper cranking power.

As for the hard starting when hot, try giving 1/4 - 1/2 throttle while cranking. That usually helps it to start if it is flooded from fuel expansion as Don mentioned. Also, a weak coil, or maladjusted points/timing can also make hot starts harder.

Merle

[NJpilot]

Thanks guys for all the rest tips and info.  My dad adjusted the points as they were off a bit. Will see if that helps. And will see about the float level too and I'll try the coil cooking tricks too. 

[MBF]

You may also want to check to make sure that the heat shield over the fuel pump is in place, and insulate the fuel line between the pump and carb.  If I'm running ethanol gas I've had times where the vehicle would start to vapor lock after sitting when hot-even idling.  The insulated fuel line seemed to help a great deal-but I've also tried to run non-ethanol gas in the older stuff that sit in the garage.

[DrDoctor]

   I concur with the others – a well-maintained 6v system will function just as well as a 12v system, we’ve got a ’46 Plymouth Special Deluxe club coupe (while admittedly not a truck, the principals remain the same) that’s 6v, but I rewired it using a Ron Francis harness, they were there when I needed them with questions, and it works great!!! As for the headlites, I purchased a set of halogen sealed beam units from my local auto parts store – didn’t cost any more than a regular sealed beam units would have (if I could’ve gotten a 6v sealed beam) much brighter than regular sealed beams, and they draw less amperage than the regular sealed-beams. Thx.