1986 F250 300 i6 efi conversion, SAS and more

[86f250straight6]

I finally got around to signing up with photobucket so I can post some pics here of my 86.

I bought this truck for $300 mostly for the body/frame and the transmission. It had an efi 302/AOD with multiple broken piston rings. Did some searching and found a 1991 f150 with a good running 300 i6, so I bought the motor, wire harness, motor mount brackets and ecm for $400.

I printed out the wiring diagrams and cut open the 91 harness and eliminted all the truck side stuff and emissions wiring so I had only what was needed to power the ecm and necessary sensors. I decided to keep the AOD since it required no wiring and I had a manual transmission ecm for the 300 so it worked together perfectly.

After I had it running I decided the stock ttb suspension was garbage and went looking for a set of 99-04 super duty axles to swap in. The main reasons for this were to have a solid front axle with modern sealed bearing hubs and rear disc brakes. I found a set in a 2001 f350 srw for $600 with a dana 60 front and full floating sterling 10.25 rear with 4.11 gears.

The rear axle was a direct bolt in swap, the only difficulty was having to swap yokes and find the correct conversion u joints to get the 86 driveshaft to work. The front axle was a little bit more of a job, you could almost squeeze it in there on a stock truck, but the spring perches are about 1/2 inch wider on the superduty axle so you have to stretch the springs a bit to line it up. I decided to build my own version of the skyy manufacturing rear shackle conversion kit instead, and built my new spring hangers to accomodate the difference in width. The whole job took a 3 day weekend to complete from measuring and designing to welding it all up and installing. Considering the time spent fabricating I could have just ordered their kit, but I believe mine is built alot heavier than their design so it was worth it i guess.
The truck has ran as my main work truck only semi-complete for the last 2 years issue free, now im taking it off the road again to do some more renovations. Here are some pics of the build (not in any particular order)
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[86f250straight6]

more pics...
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The 300 i6 installed and running good

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Dual electric fan conversion

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01 Super duty donor axles with 4.10 gears

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Solid axle swap after a few thousand miles on it, zero alignment or ride quality issues so far

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general pic of the heap before takin it off the road

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Out at work on a welding job... So far its held up well to the abuse lol

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Kinda recent pic with the old bed removed. I got rid of that rust pile to do some frame repairs and build a flatbed for all my welding gear

[Wesman07]

Very cool.... I did almost the same thing lol

[86f250straight6]

I still havent sent up notifications so i have no idea when someone replies but to check on the post. Do you have any pics of your truck? what year axle did you use? Ive always been a truck guy this is my 7th bullnose ford ive had but the first with a 6.

[bubba22349]

congrats that looks like a real heavy duty rig!

[Wesman07]

I do, but I’m not sure if I can post them. I used an 86 kingpin axle/ 10.25.

[86f250straight6]

Thought id post a few new pics since the bed was finished and its been back on the road a while [image][/image]

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I also have picked up a 96 engine with only 82k miles that I have given the once over and am quite pleased with the condition of the internals. I swapped out the oil pan as it was a bit rusty and replaced all gaskets and painted it industrial gray (pics will come soon)
This was a great find for me since the 96 comes with a crank position sensor and tone wheel, hyper pistons, with lower friction metric rings i believe. I plan to keep it speed density for now since with all my emissions deletes the obd2 computer would lose its mind, whereas the SD computer doesnt even know its gone.

[86f250straight6]

Hopefully with these 96 hyper pistons i can squeeze some more power out of the thing without constantly worrying about pistons breaking. Eventually id like to experiment with some tuning methods on the obd2 harness and computer and see how much i can improve power/driveability in the low to mid throttle range. That will have to wait till I get around to rebuilding the engine that the 96 will replace, which I plan to upgrade to everything arp, a custom piston and maybe a head if they are available a year from now or so. I would like to go with forced induction at the same time, which is the main reason for bulletproofing the motor. I may not put it in a truck though, Im tossing around the idea of finding a bronco or possibly a car, but thatll be decided once i have the motor ready since I have very little space for vehicles that dont run.

[Wesman07]

Have you looked into “stinger pimp”? It’s basically megasquirt 3 that is already set up as a replacement for your obd1 computer.

http://www.stinger-performance.com/universalparts.html

You can get that first, and play with the setting and get comfortable. There are some power gains to be had with just tuning.

Then, you can build any motor you want and be confident you can make it run well.

I will be taking the same steps. There is a turbo in my future with a stout bottom end

[86f250straight6]

I think it was you showed me that setup before. I like it, once i get the motors switched around i may try to convert to that. I think theres alot to be gained with tuning on a stock engine when emissions isnt an issue. My AOD transmission is not ideal for the trucks purpose either, a 5 speed or even a 4 would make a huge difference. Im not sure if a lower stall non lockup converter would help or if im better off just going with a stick. I do like my automatic overdrive so i can talk on the phone and drive lol

[Wesman07]

I really like my under drive trans for moving loads. I shift into 3rd by 25mph, but man it is a treat to make slow tight maneuvers. I do wish I had a fifth when I’m empty at highway speeds.

Driving my truck gives me a reason not to talk to people.... probably one of the reasons I like my truck so much lol

[Humming]

Going to ask some dumb questions because I'm clueless

On the SAS, for the front end:
Did you use the driveshaft from the super duty?
Is the steering still the normal frame mount or did you have to do something different/relocate it?
So did you end up relocating the perches on the front axle or just like with the misalignment? I couldn't quite make sense of what you described above.
I assume this required custom brake lines all 4corners? Did you keep the same master cylinder?
Are you using manual hubs or autolocking?


Thanks!

[86f250straight6]

On the front driveshaft, I believe the stock 1986 shaft would not have worked as it only had a single u joint by the transfer case and the amount of lift would have been too much angle where it could bind when the suspension drops or hit the crossmember. I ended up making a custom trans mount and dropped crossmember for more clearance, and used a driveshaft out of a 90’s dodge and cut and welded the super duty yoke on the axle end of the shaft, and found a conversion u joint for the double cardan end that goes to the np208 transfer case.
Newer super dutys use the round flange with 4 bolts instead of a traditional yoke. i think the switch was around 02-03 so i had to get a 99 shaft with the older style yoke.
This is all due to the 10 or so inches of lift ive done with the axle swap. IF you dont lift the truck more than 2” you could probably use the stock super duty front shaft with a conversion u joint to fit the transfer case.

[86f250straight6]

As far as the front axle goes, On a 80-97 the shackles are in front of the axle and the fixed point of the leaf spring is in the rear. A super duty has the fixed point in the front, and the shackle is on the rear of the spring- this design supposedly helps keep the axle from wandering around at highway speeds, as well as help prevent breaking a spring if you jump curbs or climb steep banks. Ive noticed rear mounted shackles absorb the hit better than a front mounted shackle.

Since the spring perches were 1/2” wider than the OBS i made my own fixed mounts where the old shackles used to be, and made them 1/2 wider to accept the SD axle spring width. Where the old fixed points hand on the frame behind the front axle all you have to do is hang the shackle off the hanger and shim it out 1/4” on each side for it to fit.

Look up “sky manufacturing RSK” they make this whole swap as a kit, i basically copied their design and built it myself with a little thicker steel. They make several kits in varying amounts of lift, I built mine at approx 6.5” of lift max but made several sets of bolt holes so i can adjust up or down in the future for other changes.

The stock SD steering will fit into an 86 pitman arm and works perfectly with no modifications. Also, strangely enough the SD brakes all use the same fitting as the 86. I did use the SD hoses to fit the calipers, but the stock steel brake lines will thread into the SD hoses so no changes there either. Im using an 85 f350 master cylinder with a hole drilled between the two reseviors near the top so the fluid levels will equalize since the rear reservior of the mc is smaller for drums its not enough fluid for calipers so the hole keeps the rear from sucking dry over time as the piston moves out as the brakes wear.

[86f250straight6]

I believe a super duty mc and/or hydroboost is a pretty easy swap, but the old mc with 4 wheel discs is already damn impressive, i dont see why i would need to make the brakes any more powerful than they are now: At 55mph if i were to stomp on the brakes id get thrown out the windshield lol.