The GMC CCKW

I am going to convert my Chevy to 12v while I am doing the restoration. I can buy an off the shelf conversion kit for the GMC but I am not sure whether or not the alternator will fit. So, what I need to know is, if the the mounting for the alternator is the same on the 235 Chevy engine as on the GMC 270 engine.

Thanks

What you have to do with either engine is to get the lower mounting position away from the engine so that you will have enough adjustment of the alternator to take up the slack in the belt

From memory: what has worked on some engines (GMC, Chev, new, old) is to just make a flat plate that blots to the engine than the oringinal generator mounting bracket bolts to that does this moving of the mounting bracket away from the engine.

On my Chevy Fire Truck I converted to 12v using a AC Delco alternator.

I had to weld an additional piece of metal to the orginal mounting bracket. I needed to move it away from the block and forward 1 inch to accept the line up of the alternator pulley to the existing line up of the GM belt. Due to the shortness of the alt shaft there were not alot of pulley choices available in the 235 belt thickness.



It is pictured above. The holes toward the center of the bracket are the originals. The welded on piece is toward the viewer witht the holes drilled to mount in the same place on the block. Alternator spacing was accomplished by the use of washers and nuts.

For the top adjusting bracket. I happened to find a bracket I had (from a Saab) that matched the distance and curve that I needed.

Bill

Ideal thanks guys . I think there are few more things I need to know, but I can't think what they are at the moment .

it has been my experience that sometimes they thread-seal loctite the nut for the pulley one and that you may have to heat the nut a little to get the locktite to release if you have to change the pulley. If so, replace the front bearing as you may have damaged it with the neat.....

Also, the regulator and brush assy is cheap. Replace it if you have it apart.
It will then last the life of the truck

Thanks for that, but I think the kit already has the correct pulley on the alternator. It also comes with a new alternator bracket, so I shouldn't have to modify mine .

Paul,

Being that we are in the colonies we are using rebuilt GM electronics. Is your choice GM or will it be a Bosch or Lucas <GASP> piece of hardware.

It has been my experience with automobiles that Bosch stuff mounts up differently than AC/Delco.

Bill

it is a Lucas alternator which comes in the kit.

No Offence ,Pop

But didn't Lucas use to make referigerators?
And isn't that why you Brits drink warm beer?

Cheers
John

As long as we a piling on.....

Lucas...The Prince of Darkness!

.....and for you Non Colony types, remember the C section belts available in the UK are different in section to the U.S. type C section, and they DONT fit the pully's correctly. As such wear is enhanced and belt failure IS premature.

The original dynamo pully WILL adapt to fit a Lucas alternator, and this simple adaption will save so much heart ache later on.

Mixing pully types IS a short route to disaster, something I regret kit manufacturers ( certainly in the UK ) have yet to learn.

I may be speaking out of turn here but yesterday Frank von Rosenstiel stopped by for lunch and said he is in the process of making up 12V generators. Frank's day job is an alternator rebuild tech for Mercedes Benz so whatever he comes up with will certainly be worthwhile. He will use CCKW generators. Also I seem to remember someone on this forum was looking for an early civilian dash. Frank now has them NOS in stock.
Cheers, Barry

I will see what comes with the kit with regard the pulley and belt. I'm not too worried either way has I have a new correct U.S. belt anyway so I can just swop my pullies if need be.

A 12v generator would look nice though. Keep the original look of the engine bay, with the convenience of 12v

Pop, the pullies are not a straight swap, the original GMC will need to be machined to fit the shorter shaft of the Lucas unit. Just as Bill identified.

Not a problem, I can get this done at work on one of our machines.

A cheaper way to do it is to use the Bosch alternator from a scrap Mk4 Escort, it is a very reliable unit and utilises a split pulley which can be spaced out to the correct size for the fan belt.