Who's done a 12-Valve Cummins 5.9 Conversion on their '80-86 Ford Trucks? Can you provide any information on your conversion, engine mounts, what parts you had to modify, how you handled the fuel tank/lines (if gas), what transmission/mount, intercooler/radiator/charging system, etc.

Was there any trimming of the factory firewall or AC components? How you handled the extra weight of the Cummins? Do you have pictures or a write up of your conversion? Would you have done anything differently now that your truck is on the road?

I have an '83 F-250 Reg Cab 2wd 351w/C6. It is very sentimental to me as my Grandfather bought it new and gave it to me a few years ago because I loved the truck when I was a kid, and still do. I sold it soon after when I had way too many vehicles, then bought it back last year since I thinned my herd and always felt sick about selling it. The motor is locked up. A few hundred bucks and I can put a new shortblock in it and all the hi-po goodies I bought for it before it seized) But since I've had 3 Dodges with 12-Valve Cummins engines...I've been thinking about doing the conversion.

Now, my Dodges were ALL modified trucks, but used as daily drivers, even the 650hp truck. All of them got over 24mpg, and never let me down for the last 7 years of owning them. I know these motors well. I sold my last Dodge to fund the build of my '56 F-100 which is my daily driver as of right now, usually about 500 miles a week! The '83 F-250 is supposed to be my spare vehicle and my trailer hauler for my '53 Ford Customline Gasser, since the F-100 is not only too low to pull the trailer, but too short of wheelbase, and too light weight to do the job. Well now that the F250 engine took a dirt nap, I've been thinking about doing the diesel swap in it, and have it back as my "backup" truck and my hauler.

I know about the 4BT swap site, and fordcummins.com, and destroked, etc, but I want to hear from the guys that have done the conversions themselves.

I'm a gearhead, hot rod builder, drag chassis builder, and custom metal fabricator and I can handle every aspect of the conversion myself, but I just want to dive into it with some idea of what issues I will be dealing with aside from the obvious facts that I'll be modifying stuff to make it fit.

I'm thinking I'll use a '97-early '98 12-Valve out of a Manual Transmission truck for the extra power over the older and auto equipped engines. I'm not sure if I would want to keep the truck auto (and if I do what transmission I'll use) or if I want to run the NV4500/5600, or a ZF-6spd with adapter. I'd probably use a factory diesel tank from a 6.9 or Powerstroke, or maybe a custom aluminum or stainless tank that I can build myself. I'd run an intercooler setup, but not sure what radiator/intercooler to use (Ford, Dodge, Combination of both, or something different all together. I would purchase a new set of the HD front coil springs to keep the front end from sagging, along with rebuilding the whole steering/suspension. I would handle the brake booster by running a Hydroboost unit from an older F-450. I can have the PS hoses made in about 20 minutes down the road. Not sure about using the Ford gauges as of yet. I'll build a full custom single exhaust for it from the turbo back. I want to retain the factory air, but using the Dodge AC Compressor. I just want the truck to appear as it rolled off the factory floor on the exterior, but hiding a 12V Cummins under the hood.

Sorry for the long winded post. Anything helps! Thanks.

 

Nobody done this conversion?

 

I seached 6BT swap... https://www.ford-trucks.com/forums/8...mins-swap.html

 

I did it on a 92, which for the most part is the same. It all depends on what way you want to go, as to what parts you are going to use, what you are willing to spend to buy the ready made parts, or are you going to make them yourself, intercooled or not, and the like.

I fabbed pretty much every custom piece my self, and if I do another, the motor mounts will either be of the eye bushing style, or fully horizontal mount. I followed what Ford-cummins.com did as far as the mounts go, and never again. The mounts can't handle the slope, and keep sinking. I have shimmed the passenger side up twice to keep the turbo out of the air box. Some use different manifolds than the Dodge, I kept it because I didn't want to have to get custom pipe fit. I also opted to stay with Dodge type transmissions to keep the starter on the driver's side, away from the exhaust. It is way easy to change the starter, and from what I have seen, the starter lasts longer than using the Powerstroke starters on the passenger side.

I started out with the Dodge auto as that was what I had, but it didn't hold up to the constant 20k loads the truck had to handle. It now has a NV4500, which does great.

Mine is intercooled, and with some minor modifications, the intercooler fit behind the grille. The trouble you will have is that the grille on the 80-86 tapers back at the bottom, so there is not enough room for an intercooler behind the stock grille without major modification. One solution has been to go to tube grilles to get the clearance. I also used the Dodge radiator, since I was pulling out a 460, the rad support was flat at the bottom, rather than dished down like most of the diesels of the time. The Dodge rad fits perfectly, and cools the motor just fine. The 460 rad had the hose hookups on the opposite sides, as well as would have require major surgery to get the rad out due to the intercooler pipes going over the top of the lower brackets,effectively blocking it in.

Since I took out a 460, I didn't do anything about the springs up front, and it has been fine so far, been completed for over 4 years. For your needs though, you would need to change the springs to at least the 460 springs, or diesel springs.

The 351 frame has a big hole in the frame for the oil filter to go through. You will need to cover that and make the mounts off of that. The motor mount towers off the back of the frame need to go. The mounts for the Cummins will match up with the frame cross.

I did not have to do much with the firewall, but I did bend the seam lip to make it easier to get the rear valve cover off. I have plenty of clearance between the fan and the radiator. Since you are doing it to a 2wd, it makes things a lot easier and cheaper to do this.

Reread your post, and one thing I want to address: the a/c pump in stock location requires notching of the frame. Not impossible, I did it, but then the mount settled, and broke the fitting off the back of the compressor head. There are some mounting configurations that move the pump upward a ways that gets it up and out of the frame area. Of course, if you follow what I said about the mounts, then it shouldn't be an issue.

On the gauges, I just stayed stock and made conversion fittings to hook up the gauges. All of it is NPT, so it all hooks. The brake booster I have is still the vacuum unit, as the brakes on the Dodge were also vacuum. If you find a unit with a hydroboost, then it would clean up the left side motor mount a bit. Mine cleared fine, but some don't.

 

fellro86, I would love to see some pics of your conversion; although I saw another post where you said they were lost to a computer crash. I'm working on picking up a sweet '91 Dodge W250, with an intercooled 6BT in it. I was thinking the same as you on the radiator, why not just swap the Dodge supports and factory radiator for the Cummins in at the same time?! Would be very easy to make the dodge drop in mounts work. On the topic of the intercooler, I was looking at the donor truck and then looking at my truck and it seemed like I would have room to fit it as it doesn't look too thick? How extensively did you have to trim the grill? I see your signature says you have a 92 swapped, so you're grill mods were probably either non-existent or obviously different.

I want the swap to be SUPER clean because I've taken a lot of pride in keeping this truck nice and no one ever believes that it is actually an 86. I am thinking that the easiest way to actually swap the engines is going to be to just take the entire core support out? Is it feasible to slide the Cummins in with the Getrag attached? With the radiator support removed obviously. I have a 4 ton electric chain hoist on an I-beam in one of the stalls of my shop, so I have the grunt to do it.

 

I did use the Dodge rad in mine, was way easy as you have noticed. I do know of someone who did put a Cummins in an 86-older truck, and the grille was an issue. They ended up with an aftermarket tube grille, and issue resolved. I do recommend pulling the rad support to slide in, I initially had an auto attached to mine and slid it all in at the same time. For a few pics, check out my gallery, there are some there.
https://www.ford-trucks.com/user_gal...&albumid=22082

 

After a brief thought about building the 351w into a turbo stroker, I'm back to normal again and going to continue to forge ahead on the 6BT swap.

I've got a neighbor with a 100 gallon under-toolbox tank he had in one of his diesels. He said I could have it. So that eliminates the hunt for the diesel tank. A friend of mine bought a '90 F-250 for parts, he said I could have the manual pedal assembly since I'll be converting mine over from Auto. (I hate automatics) I'm robbing a few interior parts too since it's also blue like my '83. I plan to convert the entire interior to the later style anyway. I'm just going to collect all the main parts before spending the money for the engine/trans. I'll wait to find a nice '97 215hp 6BT and NV4500 combo.

Still looking for more photos of conversions.

 

Fellro, I know you've mentioned the mounts that you've had issues with and talking about redesigning them. Do you have a picture or drawing of the type of mounts you intend to make?

 

Check out the mounts that come on the motor you are looking for, they use the very design I would change to. If you have worked with any vintage Mopar, they also used that style.

 

Just for reference for anyone searching for Cummins Conversions in early Fords...

I drew this up a few years back when I was having some wiring issues with my '92 Dodge Cummins and couldn't get a signal to the PCM since the crank sensor wires got chewed by a thrown belt caused by the plastic idler pulley being worn. My solution was to run an external regulator, bypassing the internal regulator on the alternator, and the PCM. The regulator was from a '71 (IIRC) Dodge Ram 150 with a 318. I later fixed the damaged wiring and put everything back to stock, but I probably drove around like this for a good 8 months with no worries. Mind you the AC/Cruise didn't work because it's controlled by the PCM that was bypassed. This may help you guys doing a 6BT swap if you want to retain the Dodge Alternator.

 

Fellro, thanks, I'll look at them. Since all my Cummins trucks were Dodges, I never spent any time looking at the motor mounts and can't for the life of me remember what they look like, but I'll do some searching.

 

The pedals from a 90 will not work if I remember correctly. I want to say it was franklin and a few others who said it had to be from a 80-86 with the hydralic clutch because the 90's dash is a little different.

 

Also I just thought about this website that might have some pretty good info in it for you.
fordcummins.com - Increase Horsepower with Ford Cummins Diesel conversion kits

 

Redneck, thanks for the info. I just assumed the '90 pedals would work. I might remove the entire '90 interior/dash and use it in my '83 anyway, we'll see.

I've seen the FordCummins conversions, as well as all the other companies. Real world feedback from guys like Fellro86 is the kind of info that's priceless.

 

I know people a lot of the people put the 4BT into these trucks without fabrication of motor mounts; don't know about the 6BT, I haven't looked into it.