The GMC CCKW

I'm keeping everything stock including the engine and tranny. My question is: What did you guys to about the generator? I've tried to have different place convert it to 12 v and not having any luck.

Is there an alternator that will work? I was worried about that fat belt.

Please help- I hope to put finish up this weekend and have everything else lined up.

Thanks!

You can buy a single wire alternator from many places. You need the right sized pulley for it which are also available. If you have to replace the pulley, you usually have to heat the nut (loctited) to get it off. If you do this, replace the front bearing. You have damaged it. It is only a couple bucks. Been there done that.....

You can leave the big reg box. Move the ARM wire to the BAT term. Use the other end (gen end) of the ARM wire to the alternator output.

To use an alternator, you need to move the base mounting away from the side of the engine. Again, ther sell these brackets oe they are simple to make.

Install an ignition resistor from a 1957 Chev PU under the dash in the wire going to the filter box that feeds the coil. That way you can use the original coil.

I have a web page
http://www.cckw.org/6_to_12_volt.htm
on this subject

Would it be possible to use the 6v generator already fitted, I measured the output at 20v,so could I use a 12v regulator box with it or adjust the 6 v one to run at 12 v????.

I am like Doc. I just used the single wire alternator and did the modifications he mentioned. Works great.

>Would it be possible to use the 6v generator already fitted, I measured >the output at 20v,so could I use a 12v regulator box with it or adjust the >6 v one to run at 12 v????.

Some generators will make 2x their voltage. A couple problems arise, the most serious is that when you double the voltage, the regulator will still allow the generator to make the same amount of current. At double the voltage, that is double the wattage. The generator will throw solder from the commutator or burn up. The 2nd problem is that the relay that controls the voltage is made and the contacts designed for 6v. You could probably make it work, but the whole setup would be at the extreme end of the electro-mechanical operating range. You still have the high current brushs and an electro-mechanical regulator.

They also make single wire 6v alternators.....

Thanks for the info Dr deuce,I think I'll go the Alternator way as this seems to be what the majority advise.

In your article about 6-12v conversion you mention switches across the ballast resistor, What value is the resistor?? have you measured its value and what wattage would it be?? do you have a picture of how you have mounted the brake light switch and resistior bypass switch. I don't have any details on the chevy switches

Thanks
Steve

I am guessing that if you look at Bedford trucks from the 50's you will find the same ballast resistor and switches.

Actually, any lever action automotive brake light switch will work if it will fit and operate correctly.

I will take some pictures.

I have no idea what the resistance of the ballast resistor is but I believe it is low (2 to 20 ohms) and it gets hot as it is mounted in a ceramic block.
If you use a 12v internal resistor coil, you do not need the resistor. If you use the original coil or a 12v external resistor coil, you need the ballast resistor

I got the alternator- the pulley is the wrong size for that fat belt. Did you guys just change it out with a wider one? That's where I am getting confused. I got the mide 7o's alternator like it said, but it doesn't address that the pulley's don't match up.

I changede out the pulley for a wideer one that fit the wider belt. I got it at an alternator rebuild shop in town. Most will have different size pulleys available. In fact we just made an even swap as the wider one I got was used and he was getting a new pulley in return.
By the way, I used an air impact wrench to remove the pulley nut on the alternator. All of the torque being put to the center of the wrench, the nut came off easily.

Hi Chappers
If you get an alternator off a scrap Mk4 Escort it is a Bosch unit which is very durable and reliable and utilises a split pulley which can be spaced out to fit the standard size GMC belt. I t is very simple to alter the mounting brackets slightly to fit, I also used the original reg box just as a joint box so it still looks fairly original.

See, another happy customer....

Sorry Dr Deuce if I was repeating something you have said previously, I will have to write a thousand lines,'I must read all the Doctors work' :oops: :lol:

Thanks Degsy, I'll pick up an Alterrnator this week from a scrap yard. I've just completed bolting the Cab back together so will be finishing the Engine compartment soon, then onto the wiring

Good luck and have fun.

What about using a 12 volt generator? Im sure this has been converted to Alternator by now. And how easy is it to upgrade the guages... are the sizes of the guages comparable to 'new/modern' 12 volt guages? I have considered doing a 12 vold conversion on the truck Im trying to buy, but want to try going with a generator vs. alternator if easy enough to find one....

Try a 12 volt generator from a GM or Chevorlet pickup truck and external 12 volt regulator. You will still have to have the wider pulley on the generator.

If any of you guys want to use a 12 volt gen, I have a WW2 NOS 12 volt regulator that is exactly like the original 6 volt in size, shape, and mounting pattern avail.

Hope this helps
John

Go to an alternator. You will be MUCH happier. Generators and their mechanical regulators have reliability and maintenance issues

Only the gas gauge cares. JC Whitney sells a voltage regulator (not a reducer or resistor). It puts out 6v that the gas gauge needs to read correctly. It is made specifically for 6v gauges and comes mounted/built into a bar that bolts onto the stud of the gauge.