R&R 7.3 with 6.9, What do I Move Over From the 7.36.9???

[trj]

I need advice from the collective wisdom of this group.

My bone stock 1992 7.3IDI with 190K threw #8 rod and I was lucky enough to find a low mileage (50K) 1985 6.9 to replace it. I know about the Lucky Mod. on the DMF and moving over the glow plug/controller system from the 7.3. I also intend to move over the serpentine belt system and accessorys from the front of the 7.3engine. Is there anything else that is better or more reliable/desirable on the 1992 7.3 I should consider transferring to the 6.9 while I have it available?

Another thought I had is can anyone tell me if the injectors and IP from the 7.3 work on the 6.9? I wouldn't mind having them as spares/backup if they will.

Thanks for the advice/help!
Tom

 

[GenLightening]

Pretty much everything that bolts on will fit. The rocker arms (which should go directly on the 6.9), IP and injectors are keepers, as are the valve covers, exhaust, oil pan and I believe the intake. Anything you want as a spare you should keep.

 

[trj]

Doug,
Thanks for the response.

Are you saying I should move the 7.3 rockers over or that they are the same if I ever need them? Also are the heads the same? How about the crank shaft? I heard the two engines have the same stroke.

I guess the most important question is, is there anything better on the 7.3 I should move over?

Thanks,
Tom

 

[GenLightening]

The crank is the same, I figured if it threw a rod it might not be in too good of shape. The heads won't work, too different, but the rockers are much stronger and should be swapped, as the 6.9 rockers have a tendancy to break. The lifters and pushrods may also be worth keeping. That's pretty much it as far as I know, someone else may chime in with more, but I can't think of anything.

 

[FordGuy100]

If you have the 6.9 out, I say you should invest in some ARP head studs and new head gaskets .

 

[trj]

Ok guys, thanks! I didn't know about the rockers and had forgotten about the head gasket leakage problem with them. If you can think of anything else let me know.

Thanks!
Tom

 

[Diesel JD]

I don't think the head studs are neccessary unless you intend to turbo and boost in excess of 12-13 psi on a regular basis. A set of new head gaskets(updated ones from fel pro or victor reinz) and cleaning up the bolts and chasing the holes will leave you with a reliable engine thats good for many more miles. The 7.3 pump moves slightly more fuel, its a moot point on a stock engine but with a turbo its definitely a good idea to swap it over. I'd say get the injectors(both sets) pop tested if you can find someplace to do it free or cheap and just use the best set(no mix and matching) and grab the fuel filter assy from the 7.3 as it has a reliable water sep and the filters are readily available everywhere(if expensive).

 

[tractorman86]

i remember a while back i was toying with the idea of putting 7.3 (bigger) studs in a 6.9 to have better heads and stronger clamping force but never got around to figuring out if there is enough usable "meat" around the holes.

 

[GenLightening]

i remember a while back i was toying with the idea of putting 7.3 (bigger) studs in a 6.9 to have better heads and stronger clamping force but never got around to figuring out if there is enough usable "meat" around the holes.

There's not. Plus, the stud kits for the 6.9 are less than 1/3 the price of the 7.3 stud kit. You still have the head problems that may show up, but maybe with the stud kit it won't happen?

 

[trj]

You are all a world of knowledge. Thanks!

Doug, can you give me a source for the studs you know about for less than 1/3 the price? I need to know about that source!
Tom

 

[GenLightening]

Summit has them for $260/set (fyi the 7.3 is around $800)

http://store.summitracing.com/partdetail.asp?part=ARP-150-4069&autoview=sku

 

[icanfixall]

Drilling out a 6.9 for the 7.3 studs wont work. The 7/16x14 threads hole is already too big and you wont have enough material left for a full 1/2x13 thread in the new hole.... But if you were to drill and tap the 6.9 out to 9/16x12 you would have the very best of everything. Don't think anybody could boost enough to lift those heads.. This is a very big job going out to 9/16 on a 6.9. The heads and block will need to be drilled out. The bigger issue is will it work>>> Its best to try it on a cracked head and windowed block... Then is there anybody that has the machine shop to do this??? No way would you do this with a 1/2 inch electric hand drill....

 

[subway]

Drilling out a 6.9 for the 7.3 studs wont work. The 7/16x14 threads hole is already too big and you wont have enough material left for a full 1/2x13 thread in the new hole.... But if you were to drill and tap the 6.9 out to 9/16x12 you would have the very best of everything. Don't think anybody could boost enough to lift those heads.. This is a very big job going out to 9/16 on a 6.9. The heads and block will need to be drilled out. The bigger issue is will it work>>> Its best to try it on a cracked head and windowed block... Then is there anybody that has the machine shop to do this??? No way would you do this with a 1/2 inch electric hand drill....

i have thought about that for the 6.9 in my garage, i have a blown 7.3 i could play with. are the blocks similar enough to know if i would have a problem on the 6.9?

my cheapy way of trying would probubly be a magnetic base drill press to get a straight bore. of course i probubly couldent hold +/-.00000005 with that set up

 

[GenLightening]

I might look into that when I start taking down my spare 6.9. I could probably do it on my dads Index mill, it should be big enough.

 

[trj]

Valve train parts

One follow up question: On the recommendation to move over the rockers from the 7.3 to the 6.9, I've made it a habit to keep these items together in sets with the same push rods/rockers/lifters/cam lobes kept together. Do you all think this is worth moving over and taking the risk on mixing the sets with the ones from the 7.3? If so just move the rockers only or which parts of the valve train parts would you suggest moving?
Thanks!
Tom