heres how the story goes i have an 1984 f250 that had a 6.9 diesel with a four speed four wheel drive and i wanted to get a 460 for it. however my dad has a 79 that he decided not to finish and has a freshly rebuilt 400m trans and transfer case he just gave me. what are the chances of droping the whole drivetrain into my 1984? i know its not a simple bolt in but what trouble am i looking at. also the 1984 has a hydrualic clutch and the 79 has mechanical is there a way to convert it or do i need to make something up? thanks ya'll

 

What would be your reason to abandon the Diesel?
A couple thoughts that come to mind:
The difference in weight between the 6.9 and the 400M, the 400 being lighter. Might lead to a list of suspension and steering questions that all come after the bolt up and wiring.
Have you considered a complete wiring harness that now includes spark based ignition?
If your going to work on one motor or the other to achieve best fuel economy, which one will take the least amount of work and money to get the best return?

 

where are you at i can take that diesel off your hands....and give you an extra 400 out of my bronco :-]

i think you are in for allot of work, changing out motor mounts, you would have to probubly almost scrap the diesel harness to get a spark ignition to work in there. if they are 4 speed trucks the bell housings from the diesel and gasser will bolt up to them. then there are the smaller things like exhaust, hooking up the rad, throttle cable, battery cables and such. might also be a emissions problem depending on where you are at.....

 

it not that hard... buddy had a 84 with a diesel laying in the back (rod through the block) he had a 351w so he installed it his main problem was getting juice to the motor... I found the correct wire has ran 3 years...... things you will need...
1 correct wiring harness for the gasser (on top of the motor)
2. light tester
3. motor mounts raditor
4. use the gasser tranny
5 brian box (kinda goes with#1)
6 paitence

on the wiring of the ford it simple two wire go into the brain box wht and red one needs a countious power supply(when key is on) the other wire is the "start wire" hot only when key is in crank position...
the two battery thing would be good don't take it out...

 

having dealership experience with the 400 dont do it , it has no power ,no torque and no fuel economy , my two cents , fix the diesel

 

The 400 has lots of potential if you were scrap the OEM pistons to get higher compression, and get a proper camshaft thats not retarded by 5 degrees. It can be built into a real torque monster if thats what your after, but I am biased for the diesel, is there something wrong with it?

The 400 will probably require crossmember mods as well, so its not going to be as simple as making/modding engine mounts.

 

Dont get rid of the diesel dude it could be a torque monster the 400 couldnt even dream of being. Just ask Dave S. hes da man on these old 6.9s.

 

I just found an 86 F350 crew cab dually 2 wheel drive truck in perfect shape with no engine or tranny.

It was a 460 gasser in it's first life, I may have to find a diesel and bring it back to life again as a real truck.

 

I will sing with the rest of the group. Say No to Gas! My brother in law and I have converted 4 gassers to real truck status. We have not even looked back. The 400M would be good for a rat rod or something. My 2 Pennies

 

not on the 4x4 model unless it has a car motor then it should still fit...

 

Ditto,raise the compression ratio to about 9to1 or a little higher and put a cam with at least a advertised duration at .5 inch lift of 210 deg. or more and a 400 will scream. remember the heads on these motors were based off the cleveland design(canted valves,huge intake and exhaust runners). also install oil restrictors to help oiling probs. 400 hp is easy to get out of these motors. i can remember a hot rod mag article where they got 400 hp for under 2500 bucks out of a 400m motor. try doing that a diesel.the crossmenbers are the same on all 80 up f series trucks,only thing different are the frame perches for the motor mounts. they are rivited on so all you need to do is find a donor and get the frame perches. wiring should be a plug and play thing as long as you have the gasser engine harness,the plugs are installed at the factory on all trucks.if you are on a budget the gasser would probably be cheaper than digging into your diesel if anything major is wrong with it. average diesel rebuild in my area goes for about 5000 bucks,you can rebuild 3 400m's for that. food for thought. hard to beat the low end torque of the diesel though, well and fuel mileage but since diesel is 35 cents more per gallon in my area now the savings in fuel is starting to diminish especially after you add in the cost of additives i have been running to combat the effects of ulsd diesel.

 

There is a difference for the 460 engine crossmember, it has a secial hole for the oil filter.

Have also heard of a difference in crossmember between 2wd and 4wd for HD 3/4 tons, but not sure about this one...

 

The 460 and diesel use the same engine cross member, that doesn't have the hole for the oil filter like all of the other gas engines use. The 460 uses a filter adapter that is not quite 90*, I'm not sure if that'd work for a 400 or not, never having worked with one of those in this chassis.

 

With diesel fuel being 50 cents more per gallon in my area I don't see the advantage of the diesel anymore. Yes bla-bla tell me about the torque in a diesel and the fuel econony, Yawn!!! This is the same argument over and over. I have a 85' f250 4x4 extended cab diesel truck, It has a bad engine and I have thought about replacing it but the cost is insane $3500-$5000. You will never recover this money on a 20 year old truck. I am also going to put a 400m in my truck. All you need is a bellhousing from a mid 80's 460cid truck with hydraulic clutch assembly. I dont see why the diesel radiator will not work? You should already have the engine towers and mounts from the other truck. The wiring is no big deal. I just want to a few more years out of the truck without a huge investment and I really don't see the value in a engine rebuild.