Bushings required to install 7.3L cylinder heads on a 6.9L block

[6 Nebraska IDIs]

Ok I really need to get a game plan rolling on my brown truck again. I miss it terribly and I'm on a broke college students budget to get it running again. I've made the decision to throw the original 6.9 cylinder heads in the trash, even though I just had them rebuilt less than 2000 miles ago. If you don't know the story behind them, the machinist I had rebuild them decked them down beyond the minimum thickness for one, second the finish of the deck surface was about a 50. I could literally feel the ripple of the tooling marks in the head surface. I'm convinced theres nothing else that can be done to those heads at this point. So I'm at a crossroads. My dad has given me a set of brand new NOS Ford factory turbo 7.3L cylinder heads that have been sitting on the shelf in their boxes for years. The downside of the 7.3 cylinder head on a 6.9 block is that the heads will need special bushings to shim down the size of the bolt hole in the head so that the 6.9 stud will have a proper fit inside the head. Its been done for years on small block fords by shimming a 351W head to fit on a standard sbf. So its possible and I'm going to do it. The question I have is, if I make shims, is there a calling for them by other people? I need enough to make it worth while to make a few extra sets on the CNC lathe.
Give me your input because I want to roll these suckers out here pretty soon.

 

[Diesel_brad]

Can you drill out the 6.9 to use 7.3 bolts?

 

[rhkcommander]

I've heard there isn't enough meat to properly do that Brad, but don't know any better myself

 

[typ4]

Can you drill out the 6.9 to use 7.3 bolts?

No.

I think the locating dowels are the same od on both engines. Are sleeves really needed?
I would think only a few , 2 on each end and the middle, would suffice.

 

[tjsea]

Doesn't arp make the shims allready? 351w's have 1/2 in head bolts and 302's have 7/16 in head bolts if I am remembering right.

 

[sle2115]

Someone on here a while back posted just bolting them on...not sure if they are still active on OB. They posted several thousand miles IIRC and no problems.

 

[6 Nebraska IDIs]

I want to use L19 material for head studs, which is extremely strong and resists stretching, but its brittle as glass if its exposed to repeated impact vibrations. I'm just a little nervous simply bolting them on without shims. The locating dowels are the same size but the holes are large enough to make me nervous about them causing stress on the studs.

 

[mabc926]

What are you planning on making them out of?

I bet if you look hard enough there's probably already a brass bushing close to the size you need, might just need the center drilled out.

 

[topgunn]

stud length

I set my 7.3 heads on my 6.9 block to check things out and am using ARP studs. I need to buy 8 new studs that are longer. The 7.3 heads are 3/4 " taller on exhaust side than 6.9. I plan to check with ARP tomorrow about longer studs.

 

[IDIDieselJohn]

Why would you even use 7.3 heads on a 6.9?

6.9 heads are better.... they have better cooling....

7.3 heads have 2 big coolant passages blocked in each head!

 

[93cc7.3]

hes using what has been given to him just so happens they are new 7.3 heads

 

[icanfixall]

We have had a member that drilled out the 6.9 heads to fit on a 7.3 block. He did this with a hand drill of 1/2 inch. No special fittings or mill work. Just freehand... Brave guy right there. The 7.3 heads do have the plugs in the lower corners to stop coolant flow. Also the 7.3 head gaskets do not have this opening for the coolant flow so... Use a set of 6.9 hard gaskets on the 6.9 block to 7.3 heads. Both gaskets have the same fire rings and all but the two open coolant passages in them I have both types of gaskets and have looked them over... Measured all the coolant ports.... they are the same passages dementions except the lower opening. As for the needs of a bushing... I'm not seeing it. Is it going to be just a small flanged bushing that will sit on top of the head and go down the bolt hole a small amount... I really feel the 6.9 washer will be able to cover the 7.3 hole in the head and spread out the stress fine. The studs do nothing for any head alignment. They really shouldn't even touch the heads. A set of NOS turbo heads.... Wow is all I can say about that. This is the ONLY set I have ever heard of anywhere. You one lucky guy .... Call me if you need to Sean. You know I'm mostly always available....

 

[subway]

I've heard there isn't enough meat to properly do that Brad, but don't know any better myself

no but there might be enough meat to go 5/8 studs might run into trouble with water jackets though, so far as i know no-one has tried it. you have nothing to loose experimenting on the junk heads though.