For what its worth...I have done a lot of research on rebuilding these motors, but I have never rebuilt one myself (LOT of gassers though). I understand that the 7.3 is the same casting as the 6.9, just bored oversize. This put a lot of heat on the thinner cylinder walls on the rear of the 7.3 block. Standard practice when rebuilding these motors is to sleeve the back four (4) cylinders, which is not especially cheap. However if you are going to think about this, the idea would be to sleeve the back 4 and just hone the front 4, which would have you using the stock pistons and rods. I would be leery of pulling another .020 off the already thin walls, especially in the back. You are opening up all kinds of problems (in my estimation) like cavitation damage to the thinner walls as well as burning another couple cylinders. Thats my 2 cents.

 

Sleaving all 8 should run about $1200 complete but then you would know all 8 holes are good to go and you won't be left wondering if maybe one of those bored out thin wall cylinders is going to cavitate. Make sure the machine shop does a stepped sleave job. You might also want to have them bore # 8 first so you can see if the sleeve job cuts into cavitation in progress. If it does and the cavitation is too severe you'll be better off starting over with a fresh block. D.A.S. has an article at the Diesel Stop with a picture showing how a cavitation hole can open up when the cylinder is bored.

My engine cavitated about 50,000 miles ago and I had all 8 sleaved. The small town machine shop didn't put in stepped sleaves. A couple months ago my pyro went on the blink and the engine got hot climbing the Blues. The idiot temp gauge went a little higher than normal but didn't get close enough to the red to cause me to be alarmed. The engine still ran fine but #8 sleave sank into the block allowing blow by around the sleave when the engine was cold. The compression in #8 still held at 360 psi but it blew a couple gallons of antifreeze everytime she started up cold. The shop here was of the opinion that the block probably shouldn't have been sleaved in the first place and that the sleaves weren't stepped or pinned so that when the engine warmed up the too thin cylinder walls expanded allowing the sleeve to sink.

Mine is just another 2 cent opinion however I'm having another block made ready and am sleeving all 8 again but trying to get the job done right this time.

 

Anyone know if I could reuse my old pistons in a freshly sleaved block?
I am debating if I should just sleave all 8 of the cylinders and then try and reuse my pistons.

Otehrwise I could sleave the 1 tube and bore them out to be in a position to buy 8 oversized pistons.

I personally am leaning toward the sleaving and reuse of the pistons Oh and the machine shop would pin the sleaves for sure. I just didn't think of sleaving all 8 and being able to reuse my 8 pistons until now, duh...

New rings, of course.
If not, what the heck do you do with old pistons that are still good?
Sell them for what?

 

You can definately reuse the pistons in the rebuild. The problem w/ selling them is that while you know that they are good, a lot of people stay away from used internal engine parts (I know I do). Sleeves, new rings and you are off! I still dont think you need to do the 4 holes in front, but if you have the $$$ it may add peace of mind. Remember, thin walls =cavitation problems and engine failure.

 

I have heard that a school bus has a better cam grind. I have no idea if that is true or not. I think Hyper Max probably knows more about making horsepower than anyone on the planet. Now, whether it is safe horsepower may be a different matter. I think a power stroke does about 14# of boost, I do 11-12# with a Banks and nothing has came apart yet. Once in awhile the wastegates sticks and the needle pegs at 15+ but I try not to let that happen too often.

 

OK. So what happened to the rest of this project?

 

This is clearly before the IDI performance craze began haha. I just read half this thread before seeing the date. Kept thinking, WHY hasn't anyone said R&D cam yet haha...