7.3 idi to 6.9 idi

[IDIBRONCO]

You're welcome. I could tell that you were a little bit confused. Sometimes it's hard to explain something that you know to someone who doesn't> I try, but the words don't always come out right, if at all.

 

[Macrobb]

Here's some more questions for bbjordan. This is STRICTLY talking about non Factory Turbo engines. From what I understand, the flywheels/flexplates are completely interchangeable, right? Now if the balancer should stay with the crankshaft, then why shouldn't the flywheel/flexplate stay as well. If the balancer is balanced to the crank, then wouldn't the flywheel/flexplate be as well? Are the 6.9 and 7.3 flexplates for a C6 differently balanced? How about the dual mass flywheels? Are the ones for a 7.3 transmission and a 6.9 transmission different too? Yes I've seen two ZF5s in 6.9 trucks from the factory. You can tell because for some reason, the shifter isn't straight like the ones with a 7.3 are. They are curved similarly to, but not exactly the same as the shifters on the four speeds. How about someone who puts a ZF5 in their Bull Nose? Would you have a flywheel that shouldn't be used? If so, what flywheel should you use? What about a SMF conversion? Would that only be good to use behind a 7.3? Here's something else. Was there an option to have a four speed manual behind a 7.3? I know that gas engine trucks still had that potion until 91 or 92. If it was an option, would this have a different flywheel than the same transmission behind a 6.9? Now that you've pointed the differences to me, I'm really curious to find out more info.

It's one of those things where the 6.9 and 7.3 flywheels(and 7.3 IDIT for that matter) are balanced slightly different... But it's not enough to cause an issue, really.
Plenty of people here using NA-spec 7.3 flywheels on 6.9s, and vice-versa; I'm currently running a N/A spec 7.3 SMF flywheel on my Turbo-spec 7.3 motor. Might be a little more vibration than normal, but eh... works fine for now. (One of these days I'll actually order the correct SMF flywheel and see if there's any difference).
I've also got a N/A-spec 7.3 block with 6.9 accessories, 6.9 C6 behind it with 6.9 flexplate/flywheel. It still works just fine!

 

[IDIBRONCO]

It's one of those things where the 6.9 and 7.3 flywheels(and 7.3 IDIT for that matter) are balanced slightly different... But it's not enough to cause an issue, really.
Plenty of people here using NA-spec 7.3 flywheels on 6.9s, and vice-versa; I'm currently running a N/A spec 7.3 SMF flywheel on my Turbo-spec 7.3 motor. Might be a little more vibration than normal, but eh... works fine for now. (One of these days I'll actually order the correct SMF flywheel and see if there's any difference).
I've also got a N/A-spec 7.3 block with 6.9 accessories, 6.9 C6 behind it with 6.9 flexplate/flywheel. It still works just fine!

So I guess that you're saying that even though these is a difference between the parts, it's really minimal and makes almost no difference. I understand that it's "best" to keep the parts matched up, but they can be mixed without major issues, right?

 

[Macrobb]

So I guess that you're saying that even though these is a difference between the parts, it's really minimal and makes almost no difference. I understand that it's "best" to keep the parts matched up, but they can be mixed without major issues, right?

Pretty much. I'm not sure I'd put a 6.9 flexplate on a 7.3IDIT unless I had to(because the "jump" in weight would be much bigger), but a single "category" seems to not cause any trouble(6.9NA<->7.3NA<->7.3IDIT)

(Of course, you could also probably take your, say, 6.9 flexplate in along with your IDIT flywheel to a machine shop and have the 6.9 flexplate balanced to match the IDIT flywheel)

 

[bbjordan]

@IDIBRONCO good questions. I don't know. I'm just a guy that noticed the differences between the dampers and crankshafts, and took some pictures. I am by no means an expert on this subject. I just throw in my 2 cents every one in a while.

Didn't know that the ZF-5 was an option with the 6.9.

What we need on this site are a few International & Ford engineers to answer these questions.

 

[IDIBRONCO]

Didn't know that the ZF-5 was an option with the 6.9.

What we need on this site are a few International & Ford engineers to answer these questions.

Boy the engineers would be AWESOME! I've seen only two ZF5's in a 6.9 truck and that was 20 or so years ago. I'm fairly certain that they were both 1987's. Until I saw the first one, I thought that 1988 was the first year of the ZF5. Maybe they were really late 1987's?

 

[IDIBRONCO]

Pretty much. I'm not sure I'd put a 6.9 flexplate on a 7.3IDIT unless I had to(because the "jump" in weight would be much bigger), but a single "category" seems to not cause any trouble(6.9NA<->7.3NA<->7.3IDIT)

(Of course, you could also probably take your, say, 6.9 flexplate in along with your IDIT flywheel to a machine shop and have the 6.9 flexplate balanced to match the IDIT flywheel)

I'd agree. I was still talking N/A only. The Factory Turbo is another category.