6.9 to 7.3 swap again

[illinoisboy]

hey guys it is me again. i posted earlier about the 6.9 to 7.3 swap. i know one guy said he did it to his truck. looking for a couple of more success stories. i am trying to put a 1984 6.9 with ats turbo, into my 94 7.3 turbo. the blocks are the same are they not? the motor mounts and trannies(zf5) will mount up the same yes? i know use the flywheel and balancer from the 6.9 and the glow plug relay from my 94. is that right? i tore the 7.3 down and it needs rebuilt. this 6.9 is a less expensive option and the mechanic shop is going to guarantee it for 30 days. i should know if it is good in 30 days shouldnt i? any help is much appreciated! thanks!

 

[Dieselguy123]

well I am no expert and take what I say with a grain of salt, . Does your truck still have the dual mass flywheel, I have seen a few threads on the swap of the zf to the 6.9 and the clutch-flywheel setup has been the big issue. From what I know the flywheel from the 7.3 will bolt up but If I remember right it has been said that the flywheel is balanced differantly and that it should be rebalanced to the 6.9 specs. I would think that everything else would work. I put a 7.3 in my old 85 where a 6.9 lived and it was very streight forward. Are you reusing your serp belt system? Not sure whether that will bolt on or not>someone here should know(I would think that it would). I would say go for it

 

[Agnem]

You won't find too many that have done the swap, mostly because most of the time people swapping engines don't have a spare 6.9 laying around, and they usually either A) - get another 7.3 or B) - Get a short or long block, which means trading in a core which means getting the same engine that your giving. However, there is NO reason why you can't and it is 100% compatible in every possible way with the few exceptions that have been noted. Those who have done tranny swaps often do not bother with flywheel and harmonic balancer changes in so much as practicle. If Ford hadn't been mating 6.9's with ZF's in 87, there would be much more FUD associated with doing it.

 

[illinoisboy]

thanks all, it is getting done next week, hope all goes well!

 

[illinoisboy]

mel, the truck that the new motor is in(new to me), is an automatic, and mine is a 5spd, what changes will need to be made? i keep the balancer from the 6.9 with the 6.9 and can i use the flywheel from my 7.3? thanks!

 

[zigg]

mel, the truck that the new motor is in(new to me), is an automatic, and mine is a 5spd, what changes will need to be made? i keep the balancer from the 6.9 with the 6.9 and can i use the flywheel from my 7.3? thanks!

I did this swap just this year. I also went from a standard to Auto.
This whole balance thing has been hashed over many times. Some say it's crucial, others say don't worry about it. The thought is, that the tranny doesn't care what's hooked up to it, but if the engine isn't balanced, then it can transfer shock to the tranny and cause troubles...

Since I had paid to have my newly rebuilt engine balanced, I thought I'd make sure the new parts that went on it were too, and now it's running, I've got no regrets about that. It purrrs, and runs very sweet.

I kept the balancer for the 6.9 on the 6.9, and used the flexplate(flywheel) from the 7.3, but had it balance matched to my 6.9 one since I had already had the 6.9 balanced when I had it in the machine shop.

Be sure to check the flexplate for cracks around where it mounts to the crank. These units aren't very heavy considering the stresses they encounter, and as I have learned, it is not uncommon for them to break down in this area. I just bought a new one.

Zigg

 

[Agnem]

Well he won't need the flexplate since he is sticking with the manual. I'd say swap the flywheel and what bolts to it, and your good.

 

[illinoisboy]

use the flywheel off of my 7.3? or the one off of the 6.9(new motor).

 

[rip van sparky]

I did this swap a year and a half ago. Keep the 6.9 balancer and the 7.3 flywheel. The balance differences are negligible. I drive 162 miles a day roundtrip to work every day, 70mph, 4:10s. I have put aprox. 45000 miles on since then, pull a lot of weight from time to time as well, still can't tell a difference between the two engines, still runs great. The flywheel off of the 6.9 won't work with your zf5 pressure plate. We'll see how she does after the turbo, intercooler, G injectors, and the great Moose Juicer! (if I ever get motivated.)

trust me, I had a lot of reservations about this to, they just told me to stop whinning and do it, glad I did. 7.3s are alot harder to find than 6.9s.