12 volt conversion


The old and reliable.

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Post Tue Dec 24, 2019 10:25 am

12 volt conversion

Hi, I recently acquired a really nice 49 kb-1. If I keep the truck dead stock, what are the opinions on doing a 12 volt conversion, for reliability. What is the parts list that would need changing, and given the cost is it worthwhile?

Golden Jubilee
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Post Tue Dec 24, 2019 10:42 am

Re: 12 volt conversion

Depends on who you talk too. I run two stone stock 6 volt trucks and have no reason to change. Many do not share that view.
If your are going to change, make a list, and separate into two groups, One will contain things that can easly be replaced by 12 volt equlvent items, the other those things that can not be easily changed.
The 1 st group would include all bulbs, ign coil, condenser charging system and may be heater blower. The 2nd group would include gauges, wiper motors (although 12 volt wiper motors like the K uses were and are available, they are hard to come by.
This 2nd group needs to protected from the higher voltage, there are soild state voltage convertors avaiable that will drop the voltage to 7.2-7.5 volts, the aprox running voltage of a 6 volt system. These converters will do the trick and handle loads that vary where as resistors will not.
The starter motor can be left as is.
Lot of money to spend for not much gain in my opinion. 6 volt was run in to the 50's not because 12 volt wasn't known, but because it worked. It can still work today.
If you are thinking of adding A/C or a killer radio, than 12 volts make that easy.
As these trucks were positive ground, it also makes sense if swapping to 12 volt to swap the polarity as well.

Golden Jubilee
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Post Tue Dec 24, 2019 11:25 am

Re: 12 volt conversion

I am going to surprise CB89 and not suggest a Cummins 4bta. As much as I like the Cummins idea, it is a complicated and expensive modification. The 4bt conversion can be even more challenging for a person without lots of fabrication experience and a shop full of tools and machines. If you can find a Cummins 4bta it will be $7000 plus with the core value and a simple refreshing.
Cummins offer a new 2.9 liter plug and play Diesel crate engine. Add $10,000cdn.
Staying totally stock is not a bad idea because everything around the engine can stay stock. A V8 will not fit in the engine compartment unless you remove the original steering column. An aftermarket steering column, with a few flex joints will cost about $1000. You will need to replace the steering box. A manual Saginaw is less expensive. Power steering is more money. Add another $1000 for a good aftermarket steering system complete. Check Flaming River, http://www.flamingriver.com/index.php
or, http://www.borgeson.com/index.html
A V8 can add more speed and the original brakes will be challenged. If you add an automatic behind the V8, the brakes will not be good enough. Those old trucks relied on the standard transmission and the engine to help with slowing.
12 volt conversion is not the same problem it used to be. If your old engine is in good running condition and the electric connections are good it is perfect for you OEM experience. It might be a good idea to replace the old wire harness. If you get to this point there are persons on this forum who can tell you where to go for an identical replacement harness. Price? I do not know, but $400 would be a good guess. Buy a transistor radio to put on the seat beside you, if you need tunes as you drive. The tunes could drown out the vintage sounds of the old truck and hide some of the vintage charm and experience.
You could contact Richard De Boss at info@debossgarage.com Richard has a You Tube channel called De Boss Garage. DE Boss Garage is in Southern Ontario. Contact him and he will give you all of the information you will ever need.
I get the impression Rich is a highly skilled mechanic with lots of rebuild connections. Richard has done engine swaps. Richard was my go-to person when I needed a specialty engine wire harness for a Cummins, 5.9, 24 valve computer engine.
I would rather have tools I do not need than to need tools I do not have
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.”
Mark Twain

Rusty Driver
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Post Tue Dec 24, 2019 2:38 pm

Re: 12 volt conversion

I stayed 6V and have no regrets. I have non-resistor spark plugs and wires. It was built 6V, so much easier to just stay with 6V. Remember, it was built to be hand cranked and still start. My 2 cents.

Golden Jubilee
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Post Tue Dec 24, 2019 4:49 pm

Re: 12 volt conversion

Is there a relationship between hand-cranking and 6 volt ignition?
What are those thingees in the pictures????? Both use a 1,5/8" socket to install.
Attachments
12 volt verson.jpg
12 volt version
12 volt verson.jpg (9.3 KiB) Viewed 277 times
6 volt verson.jpg
6 volt version
Last edited by nikkinutshop on Tue Dec 24, 2019 6:58 pm, edited 2 times in total.
I would rather have tools I do not need than to need tools I do not have
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.”
Mark Twain
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Golden Jubilee
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Post Tue Dec 24, 2019 5:58 pm

Re: 12 volt conversion

I'm going surprise CB and not advocate converting to 12v. unless you want to add a bunch of electronics and gizmos,

I've owned lots of these and used to convert them all to 12v. right after I rebuilt the brakes,

Make em stop first before anything else is my theory,

anyway the 2 main issues with 6v.
slow starting: replace original battery cables with bigger, run ground cable directly to starter mounting bolt, replace weaved wire ground straps, install group 2 battery,

second complaint, dim headlights: replace them with NAPA H6006 Halogen bulbs, same sealed beam as original, brighter than 12v.

my latest truck a 1949 KB-1 panel, I left it 6v. and did these things, I'm very happy with it as is, a lot less expense than a conversion with basically same results
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Golden Jubilee
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Post Wed Dec 25, 2019 10:41 am

Re: 12 volt conversion

I read you want to keep the truck bone stock and not add a higher compression engine that needs a 12 volt system. So with the low compression engine you have:
My experience with 6 volts is that if you retain the 6 volt starting system, the engine needs to be in fair to good condition. These are 70+ year old engines. What is important to easy starting is good compression, no fouled plugs, good, heavy wiring, new coil, points and a fresh starter motor. Do as bedrockjon and the others suggest and upgrade the ground and starter cables so as not to lose cranking voltage to poor cables or connections.
Mind all of that and you will have a reliable starting truck. In my mind, those few seconds of cranking don't warrant the expense and effort to covert just to turn the motor over faster when it was designed to start and run with 6 volts.
I'm sure there will be some criticism as always, but remember opinions are like a**h0!es...we all have one and know one.
Good luck with your project, whatever you decide.

Golden Jubilee
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Post Thu Dec 26, 2019 11:52 am

Re: 12 volt conversion

If you look thru old posts, I was against converting because there wasn't a good way to protect those things that are not easily replaced with 12 volt equlvent. Since the availability of solid state converters that can keep the voltage steady with a varying load (something resisters can not do), I have dropped my objections. Others have found halogen lights and good cabling can overcome their need to change.
while these old arguments got heated at the time, they were based on more then just a preference, there was reasons for the disagreement, that was based on both side, on real problems.
I grew up with "battery balancers" on Motor coaches, required to allow 12 volt accessories on a 24 volt system, they have since been "kicked to the curb" in favor of solid state electronic converters that so the same thing in a much smaller package. Once something similar became available for 12 to 6 conversions, what I objected to became moot.
One of my heavy trucks uses a supercapacitor for engine cranking, and if I had to do it all over again, I would opt for the 24 volt unit, because it can charge off a 12 volt system, allowing for no changes to the truck other than the 24 volt capacitor and cranking motor. higher voltage allows for less current to do the same work. Less current allows for lighter cabling. All within reason, however. Once the system voltage approaches 50 volts operating voltage, the air gap in switches and relays needs to be much larger and the human skin resistance isn't enough to prevent shock they way it is with lower voltage.
It was never about the voltage, but rather the need for two systems on one vehicle that would interact with each other.

Golden Jubilee
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Post Thu Dec 26, 2019 12:03 pm

Re: 12 volt conversion

As to Nikki's comment about hand cranking. My brother had two cars that came with 12 volt and hand crank, one was a 1970 model, the other was 1967.
Hand cranks tend to disappear with the onset of alternators. A generator can start changing a battery from flat, and alternator needs the voltage to be high enough to support the field current. If an alternator is connected to a dead battery, it will not start to charge no matter how fast you turn it. Another thing was the onset of Auto trans, an interlock prevents the starter from cranking with the trans in gear, a hand crank would have no such interlock, and if cranked in drive could run over the person.
High compression isn't a death-nil for 6 volt, but the higher current (for direct drive) or larger size (for gear reduction) starters, both require more copper than higher voltage, making it cheaper to raise the voltage.

Golden Jubilee
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Post Thu Dec 26, 2019 7:09 pm

Re: 12 volt conversion

I owned a 1939 Ford Coupe. It came with a crank for starting. We could start the engine without a battery. The generator had permanent magnets in it. This made enough buzz to fire the worn-out engine.
My Dad used to run kerosene for coolant before antifreeze was available. That early anti freeze lost the ability to resist frost. Dad used to drain the coolant then heat it up in the kitchen before starting the next cold day.
Attachments
ready kilowatt.jpg
convert or you get "it"
I would rather have tools I do not need than to need tools I do not have
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.”
Mark Twain

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