Rebuild 7.3L or 6.9L?

[UMR_Engnr]

I just bought a 1989 f350 with a 7.3L IDI. According to the PO it has 223,000. So far it seems to run pretty well. I had intended on rebuilding a 6.9L on the side, adding a turbo, and then swapping it for the 7.3L. However, I am now wondering whether I should just rebuild the 7.3L that's in it.

Any thoughts?

Also, if I choose to rebuild the 6.9L, can all blocks use the accessories off of the 7.3L? And are all the mounting points the same? Ideally, I would like to find an 87 block, but if I can't it would be nice to know what to look out for.

Thanks.

 

[hesutton]

There are good and bad with both the 6.9 and 7.3. The 6.9 has smaller 7/16 head bolts and can have head gasket leaks because of this. Studding the heads can all but eliminate this issue.

The 7.3 has 1/2 inch head bolts, and head gasket failures are rare. But, they have cavitation concerns as the cylinder walls are thinner than the 6.9. They also have been know to drop valves a bit more often secondary to the change in guide design. If the previous owner has keep the coolant treated with diesel coolant additive (DCA), then cavitation would be less of a concern for sure. If not, then, you have to keep it treated in the future and hope for the best.

All the engine "add on's" between the 6.9 and 7.3 IDI will interchange (monifolds, mounts, transmissions, pullies, water pump, brackets and so forth).

Heath