I have a 1976 F-250 Highboy (4x4) divorced transfer case, with a tired 390 and four on the floor. I read somewhere that a 6.9 liter IDI (non-turbo) Diesel from a 83-87 truck should work with my current transmission. If it would work, how many other changes would need to be made?

I have my eye on a donor truck, an 83 F-250 4x4 that was rolled. The body is trashed but the engine runs and has fairly low miles as far as diesels go. The bed of my truck is shot but I am planning to put on a flat bed with recessed gooseneck to pull my 28 foot gooseneck cattle trailer.

How do the horsepower and torque ratings compare between the two engines? I'm not sure how many miles are left on the 390 and the donor truck is $500.

 

There's a few (or more) guys in the 6.9L/7.3L forum who have done this swap, you may want to post your question down there too.

 

I'd go with a Cummins 12v from a 94-97 truck. Destroked has adapter plates for all sorts of combo set ups too.

Advance Adapters is a good place to start.

If you go with the 6.9 IDI, Banks has some goodies that'd make it run better too.

 

The gear spacing is pretty bad trying to run gasser trans. I would run the T18 or ZF.

I did this swap on a '75 and never was impressed with the 6.9 mileage or power.

 

I used 86 in my 76 highboy and loved it. 83 and 4 are the worst years for the idi especially if you live where you need the block heater but you can relocate it to a hose and eliminate the block cracking problem, I belive the compression was also raised in 85.

 

what is the major difference between the 7.3 and the 6.9? I thought that they were the same block.

 

The bore is the major difference and bigger headbolts. The 7.3 is bored to much so that if you don't manage te sca's in your colant they are suceptable to cavitation and then have to be sleeved which is a dry sleeve that is way less than desirable. everything but the heads and the pistons will interchange on them.

 

No need for destroked parts in a highboy just use the 2X NV4500 and have overdrive too.

 

go with an IDI out of a 93 or 94 model. they were available with factory turbos. and a ZF5 will bolt directly to one, if its not already attached. i have the same plan, except ill but usin ZF6 which require some (but very minimal) modification to use behind an IDI. then it will go to a spicer 6041 axillary tranny with two unders, a one to one, and an overdrive gear, into a divorced NP205 transfer case. as stated, dont go with the real early IDIs...

 

87 is the best year of the idi it has the upgraded block, rockers and glowplug system and is still 6.9 so no cavitation worries. You can buy a used turbo for about the same as it cost to make the factory one right.

 

you DO realize they had the 7.3 AND 6.9 from 83 clear up till 94, right?

 

yeah that's what I'm saying. If you're plopping the whole block into the truck, then what's the major hang up to using the 7.3? It's bigger, has a turbo, and the later ones even have the ability to use all the new tuners that you can get.

 

pardon? what do you mean able to use the tuners?? if you can find a way to make a tuner work with an IDI, ill kiss my own butt hole... lol. IDI diesels are all mechanical. in fact, if you took the fuel shut-off solenoid off of one, and replaced it with a manual shut-off of some sort, you would need NO electricity to run one. there isnt a single computer controlled part of em. to make more power with an IDI, you cant just plug and play like you can with powerstrokes, you actually have to turn some wrenches. which i prefer anyway.

 

7.3s are subceptible to cavitation and cannot be bored unless you sleeve it so it is not desirable at all to overhaule. 6.9 is the same motor except with thicker cylinder walls that do not have a cavitation and can be bored quite a bit. 87 was the best year period it has the upgraded block but still has the thick cylinder walls plus it has the 7.3 rockers.
An aftermarket is quite a bit better than the plugged up factory turbo that cost around 500 bucks to make it right. 83 84 and part of 85 had the block that was prone to crack at the freeze plug hole the block heater and was lower compression too. last half of 85 and 86 were great motors but still have the old style rockers 87 has the 7.3 style rockers, 88 up is the 7.3, so either 85 or 6 and swap to the new style rockers or 87 is the way to go.

 

again, i have to ask why you say that they didnt put the 6.9 in trucks after 88?

here is a vid of a 92 with a 6.9 in it.

YouTube - 1992 F350 6.9 Ford IDI turbo diesel ATS F250 F350