Well i guess first ill introduce myself. Ive been a member hear for a long time but Ive never had a reason to post in this section before. I have a 64 f250 4x4 that is my daily driver right now with the 352 V8, 4sp and 4.10 gears. I drug this truck out of a field when i was 15 and got it running and have been using it as a daily driver off and on since and im 21 now. The 352 still runs good but is a little tired so i have been planning to build up a new drive train for it to swap in. My plan was to build a stout 390 with around 400-450 ft-lbs of torque. Then i had the thought of possibly swapping in a diesel and the 6.9l is really the only practical option due to size, weight, and the fact that i don't want to be a 6BT groupie. Let me just say that i have been around diesels most of my life in equipment and i respect them for what they are, work engines. Im considering this swap for increased torque, fuel efficiency, and longevity only. Im not doing this so i can have a big jacked up diesel that blows clouds of black smoke every time i leave the parking lot. There are enough tools out there to do that.

That being said im weighing my options. This swap would have to give me equal or greater power, better fuel efficiency, and longer engine life to justify the cost of the swap. This truck would be mostly a daily driver with frequent hauling and towing as well as highway trips. Im not wanting to build a 2000hp pulling truck just a dependable work truck with enough power to motivate my truck to get up and go. This is where the questions come in as i have several aspects of the swap that im unsure on and hopefully someone can give some input.

1. Right now my truck has the dana 44 closed knuckle front end. Im thinking im going to gian at least 400lbs + in engine weight. I was thinking now would be a good time to upgrade to a Dana 60 to take the weight. Necessary?? Upgrading axles would probably mean disk brakes which would mean power brakes, which means a lot of extra work. Plus i kinda like my manual brakes.

2. I know the easiest way to build power would be a turbo. Would this gain power at the cost of longevity. Im going to refresh the engine before i put it in anyway so it will already be tore down so a little bit of build up could be an option. I guess my main question is what would it take to get a 6.9l to 500ft-lbs of reliable torque. My guess is probably not a whole lot since it would only have to gain about 200 ft-lbs or so from stock.

3. I kow ill have to change the fuel system and all that but would my original in the cab tank work? Also do i need an electric fuel pump to get the fuel to the engine or is there a mechanical pump to suck the fuel from the tank to the engine and on to the injector pump. (excuse the ignorance i haven't been around the diesel trucks much)

4. What kind of fuel mileage do you think would be reasonable. If i do this i would use a ZF5 speed with overdrive. Im thinking i could probably keep my 4.10 gears but not sure. Maybe 3.73s would work better. My truck is a lot lighter that some of the truck these motors came in so that should help. I figure my curb weight should be around 4500-4750lbs by the time i add the increased engine weight and the weight of the flatbed. Would 18mpg or so be a reasonable goal?

So far i haven't found a truck of this vintage (a few newer ones but not many) with a IDI in it so nothing to really base the build off of but it also means it would be different which i like. My plan if i decide to do this would be to watch Craigslist for a wrecked truck that i can get for cheap that way i would have most of what i needed to make it happen. I would then refresh the motor and transmission before putting them in with the help of my dad (he use to be a certified over the road diesel mechanic). Any thought, opinions, and information would be greatly appreciated. Thanks guys and hope you don't mind the long post and all the questions.

 

that engine IMO would make for a great swap in that older truck !
that front axle IMO would handle the weight but with drum brakes that would make me want to upgrade to any other axle with disk on it !
sounds like you are going to keep the truck running so IMO modernizing the running gear , brakes to power , power steering , tranny would make it a cool truck !
the fuel tank could probably be made to work but have you thought about relocating the tank to underneath ? building a custom tank or finding on that will fit between the frame !
I personally don't like a turbo on those engines because of the high compression ratio they have !
some folks love turboing them , you cant give them a lot of boost any ways !
with some tweaking of the injector pump you can pick up some power , some say to use the rocker arms from a 7.3 works good , i also think that if you port and polish the heads it helps !
these engines come with a mechanical fuel pump or lift pump as some call them , it is on the passengers side under the filter near the front !
15-20 MPG would not be out of line with the set up that you are talking about , my old 86 with a 6.9 got around 18-22 MPG and it was all stock and i pulled lots of different equipment with it !
now my 90 with a 7.3 in it gets around 20 MPG witch is close to the same as my 99 ranger with a 4.0 in it !
you will need to address the cooling system , so think about a bigger radiator !
hope some of this info helps !

 

I was wondering, did they beef up the connecting rods when they added the turbo to the factory 7.3? Seems to make sense to me that when the factory started turboing them they would have maybe made some slight changes in parts to handle it. I live at high altitude so im thinking a turbo would really help. Nothing else i could set it up so i am at least running close to sea level pressure all the time to negate the power loss from altitude.

What front axles came under the front of the 80s F250s. Was it a dana 44 or a dana 60 or some kinda TTB dana 50 set up. The other issue with a newer axle is that it will be wider than mine, meaning my trires will stick out of the fenders and look stupid unless i find an early narrow dana 60 but not sure how easy those are to find.

 

the straight axles were D44 & D60 witch are popular and the TTB came in from 1980-later
and if i remember the rods were of HD design !

 

59flatbedford---Welcome to the IDI section of FTE!
The plans you have for the 64 would give you an unique truck! I will give you my take on your questions. I think the 6.9 woul give you a great base motor, as they are known to give 300K plus miles befor needing a rebuild. Adding a turbo is the best way to add power to these engines, and if you keep the boost under 10 lbs. it will not effect the longivity of the motor. As you are planning to refresh the motor I would go with head studs, as the 6.9 has 7/16 head bolts, and it is a weak point as they can allow the head gasket to give out.
The trucks that the 6.9 came in from the factory had TTb fronts on them untill the 85 F350s (I think it was) when the 350 got the Dana 60s. The 250 got the TTB with the dana 44 on the regular cabs, and the 50 on the extended cabs. I never was a fan of the closed knuckel 44, as we has a 72 F250 with a 360, when I was younger and the bearings on the kingpins were a weak point on it. That said, the 44 you have now would probably hold up, but the 60 swap would be a great update IMO.
You could use your in cab fuel tank, but you would have to fab up a fuel return line to the tank as the diesels pump more fuel than needed, and the excess fuel is used to cool the injectors. That would not ba a hard job though.
I belive your fuel economy goal is very atainable with what you are planning. As for getting a parts truck for your project, the only year the 6.9 came with a ZF was 87, so that would limit you to that year for one parts truck. But the ZF from both the 7.3 IDI and 7.3 Powerstroke will bolt to the 6.9. The ZF has a larger input shaft than the t19 that came behind the 6.9 so using a different clutch plate is needed. You probably are running a divoriced transfer case now, so a 2wd ZF tranny would work out if you don't want to go with the married transfer case system used on the 4X4 version of the ZF.
Happy wrenching!

 

Well after looking into the prices of a dana 60 i think if i did this i would leave my front end alone and see how long it lasted. I just put all new bearings and races in it and dana 60s are out of control price wise. Im not paying a grand just for a non rebuilt axle. Im leaning more and more towards this swap. Ive heard that the heads were the weak point but some money to ARP should solve that. My truck needs a new radiator anyway so getting a nice big one isn't a big deal. Looks like i got a lot more research to do.

 

After perusing around Craigslist it almost appears that i could buy two complete trucks one with a 6.9 and one with a 5 speed for almost as cheap as i could buy the parts to do it (i have found several under a 1000 and then i could part the rest out). I could just go with the 7.3IDI then i would only need one truck but i really like the fact that the cylinder walls are thicker on the 6.9l. I have also heard that the 83 and 84 blocks are weaker, should i just eliminate them from the pickings or for a mild rebuild would they be ok. I know they changed castings but do the early ones get a bad rep from people turning up and turboing old wore out motors that are about to give up the ghost anyway. Thanks for putting up with all the dumb questions.

 

i like your idea here. your fuel economy goals are easily attainable, considering that my van weighs 8000 with a 6.9/c6 and 3.5 gears with stock tires, and gets 14-15 mpg, so with you adding an overdrive and losing 3000lbs, you should easily hit 20.
buying a whole parts truck seems smart to me, as you can often buy a truck for less than an engine.
as for what engine block, i hear that the 87 had most of the upgrades of the 7.3 while still being a 6.9, and has been described by many here as the best possible block for a build. even so, any of them can perform quite well and last a very long time.
for adding a turbo, i haven't heard any horror stories from people who keep it reasonable. i've seen a few threads from guys who were running excessive boost (30+) and blew a head gasket for it, but for those who stick to the settings recommended by the turbo manufacturer, there are actually claims of increased life. that said, i'm dreaming of a turbo in mine

 

The 83-early 85 motors were said to crack around the freeze plug hole where the block heater is installed. If you live in an area where you don't have to use the block heater, this would not be an issue. The late 85 threw the 87 engines are said to be the best blocks. The 7.3 is a good motor to, with the exception of the cavitation problem, which isn't to much of a problem if the SCA are kept up.

 

Well i live in Wyoming and right now I'm at over 7000 ft elevation so the block heater will defiantly get used. Unless I use a coolant heater instead. I was just thinking of taking a 7.3 and sleeving it back to 6.9l. Lots of money and probably custom sleeves but would make for a strong engine.

 

Ya an inline coolant heater works fine. If you are going to sleeve it, I would just stay with the 7.3 displacement. Make sure the machine shop does it the right way and leave the ledge at the bottom of the cylinder for the sleeve to sit on, so the sleeve can't drop.

 

some machine shops are just so arrogant that they think they know every thing and they just bore the hole all the way through and the sleeve will fall out through the bottom and the engine becomes a boat anchor !

 

These engines do have a mechanical lift pump, just like the old carbed gassers.

IMO, the way you wanna setup this truck, it's gonna be awesome!

I love seing people swap these Diesels in much older trucks. Especially using them as daily drivers!

With a turbo engine, ZF5 in that truck, even with 4.10's I'm sure you can see 20mpg, as long as you keep it cruising around 55-60.


This '65 F250 looks to have a stock axle under it, with a heavy Detroit in it. Interesting truck!

Detroit diesel ford f-250.mpg - YouTube