Can 6.9 cylinder heads be used on a 7.3

[Sorro71]

Hi Guys,
I'm currently rebuilding a 7.3 IDI and have found myself with a bit of a dilemma. 1 of the cylinder heads is cracked. The IDI's aren't all that common here and what second hand cylinder heads I can find here, are ridiculously priced and I still have to recondition it on top. I have found a pair of reconditioned 6.9 heads for nearly the same price as 1 second hand 7.3. I've been searching around in the forum about using the 6.9's and so as far as I can tell.
1.They can be used.
2.I will have to drill out the head bolt holes.
This is were it gets a bit fuzzy, The cooling ports at the rear of the block need mods, does anyone have some more info or have any picture's they could share? What gasket should I use after the cooling port mods?
Is there any thing else I should be aware of?

 

[79jasper]

6.9 head doesn't need the cooling port mod, it's when you use a 7.3 head on a 6.9. Iirc.
Can't say on the rest.

Sent from my SM-G900R4 using Tapatalk

 

[BDCarrillo]

I would recommend salvaging the rocker arms from the 7.3 heads.

Speculation on head gaskets was wrong, see post below for accurate info

 

[icanfixall]

I would recommend salvaging the rocker arms from the 7.3 heads. I'd speculate that you would want to use a 7.3 head gasket since the fire ring will match the larger 7.3 bore, and the bolt holes will be the right diameter. You'd have to carefully check out the coolant and oil passages to make sure nothing gets blocked on the 6.9 head.

Sorry to say this but. Not everything in this quote is really accurate. Please understand I have personally measured and double checked the 6.9 and 7.3 head gaskets for fit and dimensions. I have only found the 6.9 gaskets have the lower corner coolant passages in them where the 7.3 gaskets do not. Using the rockers from the 7.3 is the correct thing to do but might check the wear point at the valve contact area. If you can feel any wear find a machine shop that can grind off the wear or just replace them. We no longer can buy the 6.9 rockers either and thats a good thing.

 

[chris142]

im thinking out loud....is there a way to put inserts into the head bolt holes in the block instead of drilling the heads out?

 

[icanfixall]

im thinking out loud....is there a way to put inserts into the head bolt holes in the block instead of drilling the heads out?

The 6.9 block can't be drilled out for the 1/2x13 thread bolts the 7.3 uses. Kind of makes a half thread so the grip for holding power just is not there. Now if you are thinking of making a threaded bushing to go from 1/2 inch bolts down to 7/16.. Nope. Really not enough meat to work.

 

[Sorro71]

Thank Guys,
I ended up finding a 7.3 head thats been crack tested for a much much more reasonable price. After a lot of calling around and emailing in the last few days, a someone who knew someone who might have one type of inquiry finally came through. Its looks as though it can be done but its definetly not as simple as boring the head bolts holes out and bolting it on like one particular supplier tried to convince me. If it wasn't for the forum members and the information available here I probably would of purchased them and ended up In all sorts of bother.