My 71 K20 Cummins swap

[diesel burner]

I started this project back in 2013 when I purchased a 71 K20 from a local plumber/electrician for the sum of $2000. They were originally asking $4000 for it, but the seals between the transmission and tansfer case were out and they were wanting to be rid of it. It had a 350/350 set up from the factory and a service box that dated back into the 50's. it had carried that loaded service box around most of its life, so the springs and bushings were pretty well shot.My first order of business was to fix the leaking seals and put new springs under it. I put Rough Country 2.5 inch springs in the front and ordered factory 7 leaf replacements from SD truck springs for the back.
Here are some pictures of it when i bought it.

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I knew when I bought this K20 that I wanted to do a Cummins swap and started reading up on what it would take. There were quite a few threads on here that inspired me and I read every word of them and studied the pictures religiously. I started looking for a donor vehicle and then life happened and I was set back a few years on finding a Cummins. In the mean time the 350 started burning oil badly so I pulled it and the transmission/transfer case out and put in a 383/nv4500/np241 setup. I also pulled off the service box and built a flatbed for it. I could have found a bed for it but a flatbed fits my needs better and I don't have to worry about the paint matching.
During this time frame I also managed to find a Dodge Dana 60 from a first gen. I built a new front crossmember with spring hangers and core support mounts out of 5/16 T1 steel, I did this to compensate for the wider spring perches on the dodge dana 60

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In 2017, I got back on track and found a donor pickup on CL. It was a 96 dodge 2500 that someone had shortened the frame on, it was 2wd, but it had a Cummins and NV4500. Only had 155000 miles but wouldn't hardly run, had a terrible miss..... After looking it over, I decided to bring it home. Someone had put bigger injectors in and a new lift pump, didn't have any of the fuel lines tight. Leaking fuel everywhere.... Anyway, I paid $3500 for it and felt pretty good.

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When I got the dodge home we realized that the miss was more serious, evidently PO had driven it with a bad injector until it damaged the pump. Number 4 had a cracked barrel in the pump.....
I pulled the drive train out of the dodge and started analyzing what I had, PO had resealed the front cover and fixed the KDP.... But in doing so created a bigger leak on the back of the motor, appears he didn't get the cam gear hot enough to slip it onto the cam all the way.... so he tried driving it on with a hammer..... drove the soft plug out of the back of the block. Can you say Gusher..!!!!!
For the next couple years I was just plugging along cleaning things up, resealing the motor,got the P7100 rebuilt, changed transmission over to 4wd, figured out that I got a Dana 80 with my dodge purchase. That made me happy, I figured it was probably a Dana 70 But tag said 80......That was one of the first things I swapped out, went for a year or so with no 4wd because my front dana 60 had 3.54 gears and my stock HO 52 had 4.10. The dana 80 had 3.55s to match the front.
The biggest thing holding me back was a transfer case. I had sold the np205 with the turbo 350 that came in the K20 and didn't think the np241 was strong enough for a Cummins. So i had been patiently searching for a round bolt pattern 205 and finally found one in winter of 2019.
I work on a farm, it keeps me really busy April thru November, so I really only have winter months to work on it. December is my time off and January and February i only work 4 days a week.... so in 2019 I wasn't quite ready to take the plunge. to be continued.......

[Dieselwrencher]

Very nice truck and great work on it so far! I'm in to watch! Bad deal on the engine but at least it had a D80!

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Dieselwrencher, I'm ok with how it worked out, with a little horse trading I was only out $380 to have the P7100 rebuilt

So in 2019 I found a core support at a swap meet that was in decent condition and I started modifying it for the dodge radiator and aftercooler. My goal was to repurpose as much of the dodge as i could to keep expenses down. I had studied Ryanroo's build extensively and even though his pictures were blurred out by photobucket I copied his idea as best I could on the core support. I was able to get the 2nd gen aftercooler in without modifying it.
During this time frame I also ordered the frame boxing and motor mount kit from Rob Bonney Fabrication. I wanted to have as much stuff as possible ready to make the swap go smoothly when I finally do it. This pickup is my daily driver and I didn't want it out of commission any longer than necessary, although I do have other vehicles to fall back on.
I also ordered a 4" Diamond Eye exhaust kit for a 1st gen dodge, I figured it would be the closest thing to fitting.
While the motor was out, I pulled the head off and did a valve job replacing the umbrella seals. Pulled the pan and checked bearings, pulled the cam to check for damage, pulled the gear housing off and put new gaskets in everywhere. Then I painted the motor Chevy Orange..... I didn't take any pictures of it out of the pickup. I painted the exhaust manifold and hot side of turbo with high heat black(surprisingly after almost a year of driving it still looks like new)

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So now I'm caught up to 2020.....
In November of 2020 I jumped in with both feet, out came the 383, NV 4500,NP241 and everything else. I pulled the front clip and removed the bed. Started cleaning the frame so I could box it in and weld in motor mounts

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The next step was test fitting the motor.....

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After hours of measuring and eyeballing from every possible angle I was satisfied with the placement of the motor and tack welded the mounts in place. Seems like I had the motor in and out 50 times, not a lot of fun.

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Now that motor mounts are welded in solid it's time to box the frame. These pieces are Rob Bonney Fabrication products, have to say it is all high quality. My only problem was his instructions said to place motor mounts 18" ahead of rear spring hangers, this was about 5" too far ahead. The problem was the pieces for boxing the frame were made to fit his measurements, so I had to modify some pieces to make it work. Not a big deal.....

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When I had all my drive train sitting on the floor resealing the motor and what not, I discovered the PO had put a South Bend clutch in recently..... it was like new. I'm wondering if the hydraulics are South Bend too. The master cylinder is not the twist mount that everyone on here seems to have, this one has 2 studs to bolt it to the firewall. After mounting it I moved on to my hydroboost, it's from a 93 chevy 1 ton. I managed to get it with the lines still attached, I reused the steel lines and had new hoses made to connect to them.... made a real clean setup.

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I had to flip the exhaust manifold to clear the heater box, because of that I had to extend the aftercooler pipe on that side. On the drivers side the original pipe fits perfect. Because the turbo is higher, I had to lengthen the down pipe for the exhaust.... I had to modify the 1st gen exhaust extensively but it was a good starting point. Other members said they had a tight fit routing 4" exhaust around transfer case, but I have over an inch from cab floor and 3/4" from transfer case. I don't think there was a single piece of the exhaust that didn't get modified.
I used the existing in cab fuel tank, I just welded a return line fitting in alongside the existing supply line.
I found a 1st gen fan hub bracket, but it still put the fan too low to use the dodge shroud..... so I had a local machine shop make me one with a piece of DOM and flat plate.
I had to cut holes in the inner fenders to allow for the aftercooler pipes, the only thing i had to do to the aftercooler is notch the top plate about 1/2 inch back to clear the hood latch.
I was able to reuse the top radiator hose, but had to find a different one for the bottom..... Napa had one with the right bends to fit.
I built 2 battery boxes, I used a F^#d regulator with the dodge alternator(don't tell my chevy it's got ford parts on it). I had a hard time figuring out where to put the air filter because of the hood hinges...
I used the dodge throttle cable, had to modify the throttle pedal a little.

[Dieselwrencher]

Very nice work!

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I got it back on the road in March of 2021 and have put over 5000 miles on it with no problems so far. I still have things I want/need to do.... I never did wire up the grid heaters, but I always park in heated garage. I would like to have a full set of gauges..... pump has modified fuel plate and bigger injectors.... would like to be able to keep tabs on things.

My cab needs rockers replace on right side... been reading up on that trying to get the courage up to tackle that job.

I have to say I am quite pleased with the Cummins swap, the power is amazing and fuel mileage is better than any gasser. I have to say if you're going to do this, do your research and do it right the first time because it's a lot of work!!
I wouldn't want to do it over because I cut corners and didn't do it right the 1st time.

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Thanks Dieselwrencher, I have to give credit to you and Ryanroo..... the 2 of you inspired me to want to do this!!! Ryanroo's welding and fabricating skills were addicting and your mechanical knowledge had me going over every post you made

So .... Thank you

[Dieselwrencher]

Originally Posted by diesel burner

Thanks Dieselwrencher, I have to give credit to you and Ryanroo..... the 2 of you inspired me to want to do this!!! Ryanroo's welding and fabricating skills were addicting and your mechanical knowledge had me going over every post you made

So .... Thank you

Thanks and I'm glad to help. I wish other Ryan would come back and post his stuff. He's in Iowa now and I still talk with him. I miss seeing his fab work. The man is a magician!

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Dieselwrencher, has Ryan got his green pickup running yet or did life get in the way?

[Dieselwrencher]

Originally Posted by diesel burner

Dieselwrencher, has Ryan got his green pickup running yet or did life get in the way?

He hasn't gotten it running yet. Like you said, life got in the way and he built a 72 K2500 long stepper before he left CO. Now he is rebuilding his old Jeep. He also bought a ramp truck he is going to build. He's on IG as whtrhno and you can follow along there.

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Just wanting to share some information today..... one of the things I notice a lot of people struggling with swapping motors is power steering lines/hoses. When I did my Cummins swap I found a hydroboost unit from a 93 chevy 1 ton. I took all the lines that were attached to it also. When it came time to plumb it in, I cut the tubing off as close as i could to the spot where it flared open to the hose fitting. I found that Parker Hose makes a fitting that crimps onto a new hose and the opposite end of the fitting has a ferrule and nut to crimp onto the steel tubing. They are called Ferulok Flareless Bite Type Fittings......
I was able to reuse my existing steering box lines and the three hydroboost lines from the 93 1 ton and came up with a real clean factory looking setup. My NAPA store was able to order the fittings and make the new hoses, I also had the option of having a local farm equipment dealership make them. These fittings are popular in farm equipment and heavy equipment repair where they use lots of formed steel lines for hydraulic lines.
These may not be the cheapest way to go, but i was pleased with how it worked for me and wanted to share. I don't have any pictures but if you go back to my above posts you can zoom in on some of the pictures and get an idea. When I google these fittings, I don't find the ones i have but like I said before NAPA had some in stock and ordered more
Hope someone finds this helpful.....

[Dieselwrencher]

It's funny you mention these. The AC pressure line on my VE24V Excursion has been leaking for years. I decided to address it this spring. Too bad my local shop I had my AC hoses made up closed. I couldn't find anyone who would crimp on any fittings on my hose or who could even find me a fitting. My drive line shop whom also deals with hydraulic parts, sourced me these same type of fittings and I was able to fix my line. It has been on there all summer with no issues. I was leery at first but from the research I've done they hold better than a crimped fitting.

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Here are some pictures of the fittings I used. The single line is the pressure line to the steering box, I just reused the steel line that connects to the steering box and attached a new hose to it. The triple lines are from hydroboost, the return line is still factory. The other two have new hoses attached to the factory steel lines