While browsing the forums looking for info, I came across some doubt that a 12 valve Cummins would fit in a C-series cabover. After an hour of measuring, it looked possible so I committed to it. First I bought a blue bird bus as a donor but didn't have any experience with adapting transmissions and it looked to be some guessing and alot of expense so I decided to go with the Allison from the bus for the time being until I got the manual stuff figured out as I needed to use the truck come spring. I ended up using the engine mounts from the bus including the front cradle, new radiator and intercooler, other than that it was a very simple swap. All in all it took me 8 Saturdays to complete and I used it from spring until a couple weeks ago. I really didn't like the auto idea in the first place and I wasn't willing to spend the money on adding the PTO and PTO gear to the Allison 545 so I could use the dump bed so it is back under the knife now and I just put an Eaton Fuller 6 speed in from another donor truck I found. The donor was a 1993 Ford cf7000 cabover with a 12 valve Cummins so I scrapped the rest of the truck and swapped in the flywheel housing sae 2, flywheel, clutch, and trans last weekend. Also using the seats from that truck as the shifter stays down and pokes through the cab between the driver and passenger seats. I now have the 109k mile 12 valve from that truck sitting on a stand I made out of the piece of frame from the cf7000 that purrs like a kitten so might need another project??? If I can figure it out, I'll post pictures from the conversion last year and take some pictures of the current 6 speed swap soon.

Engine and trans out

The 389 out of the truck


Mounts done

Bad view of the radiator and intercooler piping

Swapping in the rear axle from the bus also for the correct gearing

NEEDED air horns

First use with Cummins and Allison 545 auto other than just driving it around for 500 miles

Donor cf7000 ( not this one but just like it)

Cf7000 teardown

Shifter stays with engine when cab is flipped and has very simple linkage that is not sloppy like the c-700 was

The 12 valve from the cf-7000 wired and plumbed to run on the stand ready for sale or project???

 

That's good info on the CF-7000 parts, didn't know they used the 5.9 Cummins in those trucks, most around here had the Ford diesels.
That shifter reminds me of the one on my 83 CL-9000, shifter was on a bracket mounted to the side of the frame rail.
Good job on the conversion.
Do you think the radiator and intercooler from the CF would work on the C?
PTO's are pricy but another option is the Allison MT3060 5 spd auto, it has lock up convertor and over drive.
My 93 F-800 has that trans behind a 8.3 Cummins.

 

The cf7000 radiator will work but the intercooler piping wraps around the sides and the main frame of the cab would hit it while closing. As for the 5 or 6 speed Allison, they would typically work but being that mine was a tractor and is so short I couldn't have it any longer than the 545 was or my already only 28" driveshaft would be at a bad angle.

 

I think the key to the 5.9 fitting is not mounting it to your transmission but putting it where it needs to be and mounting the trans to it.

 

Good progress today


Linkage is hooked up and adjusted

Still need to shampoo the seats and bolt them in and bleed the clutch, then have my driveshaft shortened when my 1610 yolk gets here.

 

How long is the bed?
My F-800 is a tractor, we're going to cut the frame and add 2-3 ft in order to mount a 14 ft grain style dump.

 

It's 12 ft

 

Would you say the trans is in the stock location? I would like to do the same swap except I plan to keep the factory 5 speed as I prefer the manual over an automatic and need all the seats I can get (or keep).

I will improve the shifter as best as I can, plan to swap out the axles and will add a ramp bed as well.

 

I didn't measure where the old trans was I just took the engine and trans out and put the Cummins as high as possible so it would clear the front axle. The rear valve cover is partially under the hoop that the cab locks down on. If you take a centerline measurement of your trans input shaft I can compare it to mine. I think keeping the factory trans would push the Cummins farther forward than mine is also so could run out of room for the radiator let alone an intercooler too. If you take a measurement from the back of the front frame crossmember to the trans bell bell we could compare that too.

 

I’m looking so the exact same thing to my ‘69 c700 grain truck. It has a very thirsty 391FT and a 5 speed. I’m ok with keeping the original tranny if bolts to the Cummins and if I don’t need to move it back to fit the Cummins in. The thing I am most concerned about is it’s top speed, it does a lot of highway driving and I know the rpm difference from gas to diesel would make a slow truck even slower. Is an add on overdrive/gear vendors a good idea or just try to find a tranny built for diesel rpms and make it work with the tilt cab?

thanks
Matt
AB Canada

 

I checked mileage empty when mine had the 389 in it and it was around 3-4mpg. The trans won't be the issue, it's the rear axle, you probably have a ratio around 5.80ish right now and you would probably like something around 4.33. that's why I used a bus, for $2200 I got the engine, temporary transmission, motor mounts, 4.33 rear axle, engine already had an air compressor, sold the rest of the bus for $500 and the tires off the original rear axle for $650, made for an extremely cheap project. The 12 valve busses are getting hard to come by now they've all aged out of service.

 

Smart, my truck has the 2 speed splitter in the rear end which is nice, but il look for a different rear end. I’d like to end up being able to go around 110km/h on the highway
The engine I got is out of a ‘90s 1ton dodge, hopefully the mounts can work, if not I know my way around a welder and oxy torch

Thanks
Matt
AB Canada

 

Just from the pic it looks like the trans would be far enough back, the problem may be needing to lower it a couple inches.

 

If you check out the "ford c series" page on facebook there has been a few that have swapped the 6BT motor into these trucks, with the stock trans and intercooler from the pickup. If you search "ronnie passmore" in the ford c series group you can see what he has done to make it fit.

If you swap the engine to a diesel changing the rear gear or the entire axle or add a "brownie" aux trans

 

What did these come with for an auto originally?