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1978 Bronco - 5.9L Cummins

#1 User is offline   American Thunder 

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Posted 14 June 2009 - 07:14 AM

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My 1978 Bronco project truck, that I picked up for only a few hundred bucks about 3 months ago. No motor, trans, but I have the original NP205 case. The truck has 86,000 miles on it, so the case is likely in great shape inside.
The previous owner sandblasted the entire underside of the body and the chassis, and sprayed it with DP90 epoxy primer. It'll need some floor work eventually, as it's thin, and I plan on full quarter replacement on both sides next year. But the truck is in very good, solid condition.
The entire 6" skyjacker suspension is new, poly bushings and all.

As for a motor, I'm going to swap in a 6BT Cummins. I picked up a Cummins powered 1991 Dodge 3/4 ton dump truck with 159,000 miles on it for $1300. I already have the transmission sold, the Dana 70 is up for sale, and I will scrap out the rest of it. The Cummins motor will end up costing me about $400 when all is said and done.
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This thing runs like the day it was built. Not even a puff of smoke when starting it cold, it's an awesome motor. Looks a little rough now, but I'll spray it either Ford corporate dark blue or the lighter Cummins blue, undecided so far.

I'm buying an adapter to bolt the Cummins up to my C6 transmission, an adapter to bolt the Ford torque converter to the Cummins flexplate, and a set of motor mounts made for the swap. Of course I'm using the NP205 behind the C6. A buddy of mine owns a trans shop, so he's going to toughen and freshen the C6 for me, and I'll probably use a C6 torque converter from a 6.9/7.3 application. I removed the stock throttle pedal with the linkage, and took the pedal from the dodge parts truck to see if it would fit. I had to drill one hole in the firewall and enlarge another hole where the cable plugs in, otherwise the '91 dodge pedal and cable is a direct swap into the '78 Bronc. It took about 5 minutes.
I'm installing a floor shifter and cable, though not sure which model yet. I already upgraded the brake master and booster with new F350 parts, and the rear wheel cylinders are now F350 parts, too. Only thing left for the brakes is upgrading the front calipers and possibly installing vented rotors.
The motor mounts that Fordcummins.com sells move the engine back 3", almost touching the firewall,(the 3" body lift helps here) which means I can probably use the stock length rear driveshaft with my 6" suspension lift, as the trans/case are also moved rearward 3". This will help quite a bit in getting some of the 975 lbs of turbodiesel engine weight off the nose of the truck. Eventually, I'll order up a lightweight glass hood for it, too. Between those 2 things, the front axle should have about the same weight on it as it does with a 460 swap. I'm going to install a quad shock setup also. I may also build an aluminum front bumper to save more weight.

For exhaust, I'm running a 4" downpipe into 4" exhaust with no muffler, a single 90 degree bend, and it'll exit under the passenger door.
I made a short video clip of the 6BT Cummins running. I removed the muffler so I'd get an idea what it will sound like in the Bronco.
http://s4.photobucke...ns59stock-1.flv

When it's done, it will have 3.50 gears, 35" tires, 3 speed C6 auto, with the motor making 300 hp at 2800 rpm and 600 ft/lbs at 1800 rpm. It'll cruise at 2000 rpm at 55 mph. I may swap in a set of 3.00 gears or even 2.73s, depending on how the motor feels, to get better mileage, as this will be my daily driver, and I doubt the motor will need much gearing to easily move the Bronco.

Some guys at Cummins agreed with my guesstimation of mid to high 20 mpg, we'll see.

This post has been edited by American Thunder: 14 June 2009 - 07:16 AM

* 1983 Bronco - '95 300 converted to carb with '95 5-speed, 3.55s, 9" rear
* 1978 Bronco - Newly acquired project truck - soon to be 5.9L Cummins powered.
* 1996 EB Bronco - 5.8L auto, 160k miles- The wife's truck.
* 1977 Mustang II - 530hp 332" stroker motor, C4 "mighty mite", 3.10s in a 9" detroit locker
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#2 User is offline   Justshootme84 

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Posted 14 June 2009 - 12:56 PM

Cool swap, sounds like you got most of it worked out. What made you decide not to use the Dana70 for the rear axle? Looking forward to more build pics, JSM84
1984 Bronco XLT, 460, C-6 AT, Dana60, Sterling 10.25", 36" GYR RT-II's on H1 rims, S&W Racecars 10-pt cage kit, PRP racing seats, tube doors, Herculiner, custom "shaker" assembly.

1988 Bronco Custom, 302 EFI, C-6 AT, Ford 8.8". parting out

1986 Bronco Custom, 300-I6, NP435 4sp, Ford 8.8", new paint

1988 F-350, 4WD, 460 EFI, C-6Dana 60, Sterling 10.25 (donor)

1978 Bronco Custom, 351M, NP435, Currie Ford 9" w/ spool

1979 F-150 4WD, 351M, C-6, 4.10 gears w/ 35" mud tires

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#3 User is offline   American Thunder 

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Posted 14 June 2009 - 03:16 PM

The 9 that's in it is in perfect shape, with new brakes and all, and I really like the aluminum slot mags on it, and I didnt want to go through the trouble of doing the D70 swap, then find a D60 front and rebuild whatever it needed, and then find a set of 10" wide 8 lug wheels, too. Plus I'd end up with a lot more weight on the vehicle, which I'm trying to reduce any chance I get, to optimize mileage and acceleration. If an axle breaks in the rear, I'll upgrade to 35 spline detroit locker and aftermarket axles, same goes for the D44 in the front. That way I gain the strength without the extra weight.
* 1983 Bronco - '95 300 converted to carb with '95 5-speed, 3.55s, 9" rear
* 1978 Bronco - Newly acquired project truck - soon to be 5.9L Cummins powered.
* 1996 EB Bronco - 5.8L auto, 160k miles- The wife's truck.
* 1977 Mustang II - 530hp 332" stroker motor, C4 "mighty mite", 3.10s in a 9" detroit locker
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#4 User is offline   pwoofer 

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Posted 19 January 2010 - 10:10 AM

Hey American Thunder,

I just wanted to tell ya that is an awesome project. Great minds think alike. I have been looking for someone to put a 6BT in a '78 or '79 Bronco for some time to see how it could be done. I know that is a beast of a truck. Anyway, I was wondering if we could exchange emails so I could use you as a consultant for when I attempt my own '78/'79 Bronco 6BT swap. It may be a little ways away from now (until funds become right), but it's always good to have resources and do your homework. I greatly appreciate any information you add on to the forum.



My name is Phil and my email is pijbsme@gmail.com

Good luck with the rest of your project.

Thanks
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#5 User is offline   AdamDude04 

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Posted 19 January 2010 - 06:52 PM

Looks like a great project!

My buddy has a 67 F100 with a 1ton axle swap, and a 5.9 cummins motor. I almost want to do this to my bronco as these look pretty sweet swaps and I'm learning a ton getting his truck road worthy
89 Ford Bronco XLT
5.0 V8
322,318 miles (Daily driver)
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#6 User is offline   Krafty 

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Posted 21 January 2010 - 05:12 PM

http://fordfzone.com...-cummins-build/
81 Bronco 300 4spd, 4" skyjacker coils in front, 3" add a leaf by trailmaster in rear, and 2" blocks. 33x12.5x15, Sold my baby.
81 F150 swapped 390 with broken frame, scrapped the truck but kept the motor then sold it later for $500
88 GMC 3500 flatbed dually, 350 swap, scrapped the truck but kept the motor, now in 88 z28 Drag car
95 GMC 2500 ext cab, seized 6.5 with blown tranny and transfercase, sold for $500 with a mint body.
89 F-150 302 efi 4x4 swapped the motor but had a bunch of problems sold for 500

93 F150 4.9 4x4 reg cab long box. Current Daily
79 Ford Thunderbird 429 swap summer car. Blew a manifold parked till i can find a set of headers
69 Mustang 302 4 spd original numbers matching, red/black. almost ready for the road.
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#7 User is offline   Powerstroker 86 

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Posted 13 March 2010 - 01:28 PM

american,

are you using the 79 radiator or did u swap it out for a bigger one? im working on a 7.3L PS swap into a 79.

Thanks
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