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460 to 7.3 idi engine and transmission swap question

47K views 11 replies 4 participants last post by  steeldriver 
#1 ·
ok i have the option to pickup a '90 F-350 cc 4X4 ZF-5 for around 2k, only problems is it is high miles and is currently running a 460 fuel sucker, i have a friend who is willing to sell me his '90 F-350 cc 2wd ZF-5, for 800, truck was wrecked but engine and trans are still in very good working condition.It is a 7.3 IDI. my question to y'all is how difficult would it be to swap out the 460 and drop in the 7.3, do i need to swap out transmissions, what else needs to be swapped out during this conversion, and can anyone explain to me step by step what would need to be done to accomplish this possible swap ?

thanks
 
#2 ·
If you get the whole truck the swap should be pretty easy. Yes on the transmssion swap def. Big block is different than the diesel.
Not much wiring on either one. (well, compared to alot of other swaps.)
 
#3 ·
do i need to get a different T-case for the swap?
 
#4 ·
anyone?
 
#5 ·
Transfer case should be fine, use the diesel transmission,you may have to swap the output shaft I'm not 100% sure there.
The transfer case should bolt right up along with the adaptor housing on the rear. I did a tranny swap on a powerstroke 2 wheel drive using a 4 wheel drive transmssion. Everything swapped right over. I didnt have to change anything to make it work. Just bolted it in there. The zf-5 had a couple of different gear ratios, you may want to check which you have. Low gear and second gear on some were alot lower IIRC. I had three different transfer cases in the shop last year while my motor was out, all of them would bolt right up to the 4r100. One was OBS, one SD, one OBS a different year model. Same bolt pattern, same input shaft splines.
 
#6 ·
Thanks for the help Smorris, this is potentially a really big project for me and i need all the advice i can get with it, normally i wouldn't even consider a conversion from gas to diesel ( let alone an IDI engine.) but in time ( some time after harvesting when i have the $$$ to get it) y'all will see the "interesting" F-350 i'm talking about converting.
 
#7 ·
one more thing, ( kinda feel dumb to ask but i have to be sure) do i need to swap out motor mounts for the idi, or will it bolt up on the original 460 mounts?
 
#8 ·
Actully the 460 and diesel share the bell housing pattern. the diesel has an adaptor plate on it. The gear ratios may or may not be the same, but remember the 460 had more power than the diesel of that era. As far as the motor mounts just leave them on the diesel and they will slide right back in the new truck. It really should be an easy swap since there is very little electronics and youll have the donor truck. The main advantage of this swap would be the fuel economy.
 
#9 ·
thank you for the information, and yes the main purpose of this swap is for fuel economy, currently the vehicle in question gets 8 mpg, i want to bump it up to at least 12 mpg or better.
 
#11 ·
Ok so after some searching I did find out that they are slightly different. When I swapped out the zf out of my 460 I had it laying there when I did a clutch in a 7.3 idi and they looked close so I thought they were the same. Plus I had been told they were the same. I guess you cant always belive what you hear. sorry for the bad info, I had been wrong on this for about 3 years now.
 
#12 ·
i need some help on my pickup that was a swap, if this is still alive. also there some bad information out there on both these engines. when corectly modified and maintained the 460 will average 15 to 17 easy with no internal mods and will see a average of 10 to 12 towing. i have hit 15 towing 12k. even in hilly terrain. the 460 is fuel sensitive. which means the type of gas you get. different stations use different blends and diferent refineries even. exon or mobile gets the best. same goes with diesel. heat is a big killer of mileage with any engine, ford failed in this area. i made a simple modification to the core and increased the size to allow a 7.3 idi or 6.9 radiator to fit into my 460 pickup. so on a conversation situation it would take much to cut and weld. currently running at 130 degrees average on 460. going to install a 6 core 7.3 radiator next. then at some point change internals. i know i can get to 25 or 30mpg with these 460's. and as far as trans go, the zf5 trans in the 6.9, 7.3 idi turbo and non, and 460 are all inter changeable. the autos bolted the same but the gearing and shifters are different. now the power stroke is whats different, and theres almost nothing the same right down to the frame on a power stroke. as far as engine mounts i have seen where they bolted right in with no modification in the older frame style, 81 to 92, but from 92 to 96 it would take a lot of modifications, and isn't honestly worth putting a diesel due to clearance problems, although a cumin's would fit in this smaller frame.

now if youre still with me to my questions.


i bought a 7.3 idi f350 chassis truck that had a 460 in it. judging by what i found the engine has ran under its own since the swap and who knows when. if a person pull starts runs great. where to start. was going to try to repair wiring harness and fix bad splices. they kept the original 460 harness and spliced in at least 2 if not 3 posibly 6 different harnesses to make it work. none of which matched the engine or truck. a lot of shorts and dead grounds. i found a 6.9 liter in a salvage yard with a good harness. except 1 plug, so i pulled the engine harness and installed it. the dash should have been the same configuration. it wasn't. so i went back and pulled the dash and all the connectors. installed everything. i still don't have power to ignition switch and fuel pumps are now not working. i noticed on old harness they used the gas pumps and relays. but when i replaced it didn't have the connections for relays. on the 4 wire gas fuel hanress the orange and black wires where cut going into the fuel tanks also. and noticed i have 4 wires going into pump and diesels have 2 but 2 of the wires where cut. so i dont see a problem there.

i cant find a wiring diagram to figure out why ignition isn't working or if there's a connector missing. but being this came out of a matching harness i don't see why it doesn't work. also ignition wire to selinoid didnt work before also? possible in column? should i break down the harness and wire in relays for fuel pumps or is there another problem? i cant find a diagram of this year to go over everything.

i have worked on fords for years and tackled a lot of wiring projects but this makes no sense. got the truck cheap so trying to get it to run,

on a side note any ideas on trans? i hit 5th at 25 and can get up to 50mph. i can dead start on a hill in 4rth no problem, its in 2 wheel drive. 4.10 rear. was debating putting in a class 3 bell housing and a 12 or 18 speed. i like and need the torque but it would be nice to get somewhere in a decent time and take some rpms off of motor. was going to add a banks turbo that was installed from ford on the 6.9 salvage pickup. it is also exact fit to this motor i found out after research. from what i have researched ford didnt install many turbos in there diesels. good/bad? can get for less then $100 but not sure if its worth it. everything i read says don't.

any help on this is greatly appreciated.
 
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