The GMC CCKW

I have purchased a g 506 and was told a GMC 302 would bolt in. Now I have heard of " bolt right in" where the truth is one has to fabricate throttle linkage, front engine and other time taking changes. Before I buy a 302 I would like to know exactly what is involved in the trans plant. I might just put a ranger in front of the trans instead if to much fabrication is required.

I have been told that the 302 will bolt up to the Chevy bell housing and the Chevy trans works fine. Past that I don't know. The extra ponies and torque would be great. Any help would be great. does Civilian 302 have the same oil pan and pickup as the military 302?


Brett

The 302 will:

* Bolt up to the bellhousing
* fit in pretty well
* Give you a lot more power
* You need to find a flywheel for the 302 (small one)
* You will need to make a plate to extend the front timing cover location mount back the 1.5+ or so to the chev mount
* not sure about the radiator location. The CCKW radiator is taller then the Chev and will not fit I believe
* The stock 302 oil pan should work fine. The chev power train sits about 2" hight in the chassis than the GMC. I still have the civy oil pan in my CCKW cargo truck
* gas pedal linkage might need to be extended or a CCKW one used
*If you are using a military GMC 302 there are some other issues

Hope this helps

Thanks Dr. Duce,


I have a ranch on a hillside and want to make sure that this civilian 302 will work ok on hillsides. I would think military 4x4 vehicles would have deeper oil pan sumps and longer pick up tubes.

What motors would have the small 302 flywheel is it just 302 or will 270 work? Or any chevy flywheel? What year vehicles would I look for?

I have heard that a 270 head on a 302 will improve power bump the c.r. up a bit and will work fine is this true?

I do have a spare 235 motor.

You need to find a 50's 270 to get the right flywheel. The later engines have a 6 bolt crank/flywheel and it is different than a Chev from what I remember.

Heads are different between WW2 and 50's engines. Never swap them!

One can swap a 50's 270 head onto a 50's 302 block?

what size truck is the limiting factor for flywheel use 1.5 ton on down or 1 ton and smaller?

Thanks again brett

The 40's 270 engines had Turbo-Top pistons. The 50's engines had flat pistons. The heads MUST match the piston type

Yes, the smaller trucks have the right flywheel. The one on the BIG truck 302's has a 13" Brown and Lipe clutch and a huge bellhousing with is incompatible with the CCKW. I was thinking about taking one to a machine shop to see how much it would cost to turn it down to the correct diameter.

Beware of the ring gear. There are 12v ring gears and 6v ring gears. They can be swapped by a good auto machine shop but they MUST match the starter.

Thanks for all the good info.

Where would one get pistons rings bearing seal gaskets etc?

I believe last question: Is there any difference in oil pan and pick up tube between military 4x4 and civilian truck 302 motors?

Concerned about working on hillside with this rig and not having oil pressure.

thanks again


Brett

I believe you can easily install a CCKW 270 pickup and pan assy. My crane CCKW has a deep pan and I assume pickup.

Patrick's in AZ has pistons I think.
You should be able to buy gaskets at at good autoparts store or use the M211 ones from Memphis Equipment