My '93 F-250

93_Fummins

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Edmond
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#1
My first truck was a 1993 F-250. It was given to me by my father to drive during high school and college and I later purchased it from him outright once I graduated and got my first real job. It is an XLT, extended cab, long bed, which started life in 2wd with a 7.3 N/A IDI and ZF S5-42 5-speed. With 3.54 gears and 265/75/R16 rubber on the rear it would get 18 MPG religiously no matter how it was driven.

Unfortunately, with almost 300k miles on all original parts, something was bound to give. First the Dual-Mass flywheel started to come apart while towing a load of lumber and shingles to reroof my mom's house. Once replaced with a solid flywheel LUK clutch kit, the engine decided to call it quits by dropping a valve. With 7.3 IDI's being fairly obsolete, and rebuild parts being rather expensive and hard to come by, the poor rig was parked for a while until a plan was hatched.
 

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93_Fummins

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#2
The Diesel Power movement was getting pretty heated at the time, and the 12 valve 6BT Cummins reigned supreme on all the dynos, forums, and magazine centerfolds. Being an impressionable college student with a desire to not be outdone, I began the hunt for a 6BT donor, preferable with a manual and 4 wheel drive. I dragged my feet on a great lead; a rolled '94 Dodge 2500 5-speed 4x4....missing it by a matter of hours. I would tend to regret that bit of procrastination for quite a while later.

Feeling diesel envy, as the roar of straight piped pickups dragging the main street outside my dorms tortured my sleep, I jumped on Craigslist and found a 1989 W250 just down the road. It was manual, it was 4 wheel drive, it was a Cummins, it ran, and it was cheap! Paper was exchanged and I was off to the races.

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So I quickly hopped in and drove it to the shop...getting pulled over by highway patrol along the way for no plates (the lack of bed didn't help either). Luckily I had the title and everything was filled out properly for transfer, so he wished me luck and sent me on my way, telling me to keep the smokeshow to a minimum.

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I pulled it in and quickly got to work tearing the front apart to pluck the engine.

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93_Fummins

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Edmond
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#3
Somehow, I managed to get a little hasty removing the transmission and broke off the awkwardly designed slave cylinder bracket from the bellhousing. My dad was able to TIG it back together and add some extra beef.

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Next was to pull out the poor 7.3...

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5.9 vs 7.3....

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While I regretted not getting a 2nd Gen donor for multiple reasons, a perk of the 1st gen was that it still had a kingpin axle. I know the kingpin is pretty antiquated, but it offered easy crossover steering, a historically more robust setup than the 2nd Gen CAD axle, and live spindles. The 1st gen also had the invulnerable NP205 transfer case. The downside (kind of) is that the axle is actually a D61, not a D60, so anything lower than 4.10 is going to require trickery. This one had 3.54s, which matched my OEM Sterling 10.25 rear....for now.

Dana 61.jpg
 

93_Fummins

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Edmond
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#4
I had been fairly obsessed with the Cummins for some time, and had read quite a bit about the pro's and con's. A bit topic of discussion was the dreaded KDP (Killer Dowel Pin), so I made sure to take care of that while the engine was out. I also added a 3200 RPM governor spring and popped the stop collar off the fuel screw while everything was easy to get to.

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Time for a test fit. Liiiiiiike a gllllllove!

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The oil pan took some shoehorning to get over the crossmemeber, but everything settled in nicely. Now just to bridge the gap between the 6BT block and Ford diesel motor mounts...

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This should to the trick...

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Unfortunately, the turbo crowded the HVAC box in it's factory location. I flipped the exhaust manifold and clocked the turbo to clear the box and my dad once again fired up the TIG torch to crop the factory crossover tube down.

Cummins Test Fit 002.jpg
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New Intake 002.jpg
 

93_Fummins

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Edmond
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#5
I wanted to retain the factory 7.3 radiator because....well...it's MASSIVE and should cool just fine. This may come in handy considering that the Cummins is a bit longer than the 7.3 and my decision to offset the head from the firewall enough to remove the rearmost valve cover easily meant that a mechanical fan wasn't going to fit. Unfortunately the lower port on the 7.3 radiator required a crossover pipe to be fabbed for the coolant.

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With a little more plumbing, some fairly simple wiring to make all the factory gauges work and the stock Dodge intake heater grid, and it's now Cummins powered!

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93_Fummins

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Edmond
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#6
Now that the Cummins was in and making smoke, it was time to address the driveline. The clutch was an interesting lesson... The bore and stroke was almost spot on for the Ford vs Dodge assemblies, but the mounting was all wrong. The Dodge was a twist lock master with a bolt on slave, and the Ford was a bolt on master and clip in slave, so a hybrid was in order since I didn't want to butcher the already crack-prone firewall of the Ford cab to accommodate the twist lock Dodge master (which I probably should have done anyway) so I started pulling the assemblies apart. Naturally, the pilot fitting to the slave cylinders were different and for some reason I failed to even look at the pilots to the masters (which oddly enough would have interchanged had I looked). So, in my infinite creativity, I used a brass compression coupler made for plastic air brake lines and spliced the lined together. The coupler worked great...after fighting for three whole days trying to bleed the system. I ended up just cracking the bleeder on the slave and taping a bottle of brake fluid to the master, letting it drip into a pan overnight. Seemed to do the trick and the clutch has worked flawlessly ever since.

The front drivetrain was next, and is where the hack jobbery starts to get thick. Since the truck was 2wd with the famed Ford Twin-I Beam suspension, there wasn't much to work off of or get in the way. Hindsight being what it is, I should have taken the time to do a link or radius arm and coil arrangement using the factory 2wd buckets, but leafs were cheap, relatively simple, and fast.

First I needed to figure out ride height. I had purchased a set of 35" Maxxis Mudders and new 16" American Eagle wheels with intentions of running (which I should have), but upon picking up the mounted and balanced rubber, the owner of the shop said I needed to come look at something. I followed him into the storage room and sitting there was a brand new set of 38" BFG KM2 Mud Terrains, which had just recently come out and this was the first set I had seen in person, mistaking them for Krawlers at first. Interestingly enough, a guy had come in and put $1000 down on them for his new Duramax, but got in trouble, the truck was repossessed and the tire shop owner never heard from him again about the down payment. So, for the same price as my 35"s, I could have 38"s. What college kid would turn that down? Luckily my dad was in the market for new tires, so he bought the 35"s and I had the 38"s mounted up on some new 17" wheels.

38s or 35s.jpg

Sizing things up...

Sizing Up The Treads 002.jpg

It was going to take a little more lift than the factory Dodge flat pack, so I whipped up a bastard pack using the Dodge main leafs and some F-350 Cab and Chassis rear leafs as they were narrower to match the Dodge main and we just happened to have some Ambulance package leaf stacks laying around.

HPIM0105.jpg
 

93_Fummins

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Edmond
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#7
The front end hackery continues with an overly elaborate shackle reversal drop box crossmember...

HPIM0114.jpg

And some bolt on rear shackle mounts, since I didn't want to weld to the frame...

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In the theme of low budget hack job, I did a shackle flip in the rear and built some nun-killing mega lift blocks for the rear out of some 3x6 thick wall box tube...

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Riding high on it's own weight finally!

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93_Fummins

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City
Edmond
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OK
#8
Naturally, a brodozer Diesel Power build wouldn't be legit without a set of pillar gauges and stacks. I opted for Boost, EGT and Oil pressure as I never really have trusted the OEM Ford dash cluster oil gauge, and I'm not running an automatic to worry about overheating. My dad fabbed up the Y-pipe out of two 90*s cut and Siamese welded together since premade Y-pipes are outrageously priced and T-piping it is pretty lame for flow, in my opinion...

HPIM0103.jpg

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93_Fummins

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City
Edmond
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#9
I ordered up some generic lift shocks, a crossover steering arm and random tie-rod tidbits to finish up the steering. I used a Chevy 1-ton heavy duty tie rod end and weld in bung on the axle side and spliced in the factory Ford turnbuckle on the steering box side to keep adjustability and replacement as easy as possible. The factory Ford box actually turns the 38"s quite easily without any modification or assist cylinder. I was pretty impressed.

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Obligatory poser shot of it's first time in the sun under it's own Cummins power!

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93_Fummins

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City
Edmond
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#10
The rear would never survive with mega lift blocks, so some traction bars were needed. I decided to let my creative juices flow and fabbed up a set of box tubes with 1/2" rebar lattice work for decoration. I also made the traction bar brackets bolt on, again not wanting to weld to the frame rails since I don't trust my welding that much.

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With my creative juices overbuilding seemingly trivial accessories, I decided to cobble together my version of a Road Armor bumper...only in 3/8" variety.

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And to keep with the theme of being slightly different and obnoxious, I went with 7 cab lights, since this cab didn't have any and definitely needed some for the complete big rig look...

HPIM0183.jpg
 
Last edited:

MrBeep

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Dillsboro
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#11
Great story :thumbsup: Very interesting and turned out with that AWESOME classic vintage Ford appearance. :wave:

How is the fuel milage?
 

93_Fummins

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Edmond
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#12
As with any hotrod, soon you find the limitation of parts and the pitfalls of poor tuning. This thing ran hot...VERY hot...with a pump turned to runaway, a custom ground AFC pin, and no intercooler. Sure, it would black out the freeway, and bark the tires through 3rd gear, but a high mile, 20 year old drivetrain can only take so much. The transmission started growling...the transfer case leaked...and the No. 1 piston threw in the towel after the umpteenth 1600+ degree F pull down the highway terrorizing the other oilfield brodozers. So, after less than 1 year on the backroads of Oklahoma, the F250 was down with blown motor again.

The No. 1 piston melted the crown, seized all the ring lands, and scored up the bore to the point of no compression.

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With the stock bore damaged pretty badly, and a love/hate relationship with the VE injection pump, I began the hunt for a P7100 powered donor. My dad caught wind of a container truck going up for sale at the dealership he gets parts at for work that just happened to have a recently remanufactured 6BT in it. So, for less than what the W250 donor cost me, I drove home a massive 1994 Ford CF8000 cabover box truck with a fresh Cummins ReCon P7100 injected 6BT and enormous Eaton Fuller 6 speed. I pulled the engine and gave the container bed and transmission to my dad, sold the fresh low profile tires and wheels to my uncle for his road tractor, parted out the cab back to the dealership, and almost broke even.

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93_Fummins

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Edmond
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#13
I decided to be a little more mindful of the tuning and heat this time around, so I quickly sourced a '99 Superduty intercooler off of fleabay.

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Installing it was actually pretty straightforward in the OBS core support area. A little trimming of the radiator flanges, reworking the hood latch, and fabbing up some support brackets and it was in.

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The oil pan was significantly larger on this "medium duty" motor compared to the Dodge....and I wasn't about to lose updated oil capacity...so the crossmember needed some massaging to make room.

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I also took a moment to redesign the motor mounts to a round captive isolator bushing. This made install and removal of the engine a little easier than the previous hybrid, and also needed to be done to make room for the Bendix air compressor and Vickers hydraulic power steering pump on the driver side.

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93_Fummins

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Edmond
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OK
#14
Going with the idea of better tuning and cooling, I added an updated intake horn, three-piece exhaust manifold, and S362 turbo. I bumped the 190 HP pump timing up a bit....perhaps a bit too much as it hammers pretty hard at idle, but has the snappiest mechanically injected throttle response I've ever experienced so I live with the rattle. A set of EDM'd Bosch injectors, equivalent to 5x.012" or roughly 425 HP rated flow potential, were installed to give me a bit more spray potential should I ever rerack the pump. And v2.0 is born!

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Shortly after the rebirth, the transmission started growling pretty bad. The Getrag 360 was notorious for washing out the input bearing due to a number or reasons compiling together... The trans was designed to be run with 5w-30 motor oil, but mot people put 90w in them which starved some of the smaller oil ports when the fluid was cold. The fill port is also machined fairly low in the case which further starves the input. These combined with a hard life behind Cummins torque had the input bearing pretty trashed. Oddly enough the bearing race is machined into the input shaft, so I had to buy a new input shaft and commenced to rebuilding the transmission on the back stoop of my apartment. I went ahead and rebuilt the NP205 while I was at it. My duplex neighbors about lost it when I popped the bearings loose with a Harbor Freight press in my kitchen. Needless to say, they were stuck on there pretty hard.

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Offerings to the gods of speed and power...

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93_Fummins

CJ-8 Member
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City
Edmond
State
OK
#15
Great story :thumbsup: Very interesting and turned out with that AWESOME classic vintage Ford appearance. :wave:

How is the fuel milage?
Thanks! With the 38"s and 4.10's, it got about 18 MPG empty. I've since gone to 35"s and it's about 16 MPG empty and 12 MPG loaded with my YJ. If I drove a little slower (I'm a 10 over the limit kind of driver, unfortunately) I would probably get better, but 4.10's are too low for 35"s and the revs are way too high. Has great power and runs super cool, but cruising is miserable. I have 3.73's for it which will help get it back where it needs to be, but that's version 3.0...
 

sdsupilot

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OKC
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#16
Great story! That is a huge undertaking to do both a Cummins swap and 2wd to 4wd. Makes for quite a capable tow rig.
 

Cmath

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Woodstock
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#17
Nice thread ! I am a diesel (cummins ) nut also. I just ordered the R2.8 engine and I'm not even sure what it is going in .It's between the CJ8 and CJ7. Most likely the 7 gets it because it's not as heavy as the eight. My towpig is a Ram 2500 5.9 with just shy of 800hp(778). Way to jump back in there!! Keep it up.
 

gr8dain

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Ashburn
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VA
#18
Nice build. I just picked up a beater 89 F250 with the 5.8 liter gas engine. Working out some electrical gremlins. Looking at this thread makes me feel like a wimp complaining about finding the break in the power to the reverse lights.

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