I never said they were dumb questions. But you are right, you don’t know till you try. Just because the crank ran in one engine doesn’t make it “good”. If it’s got grooves worn into it, the old bearings probably have corresponding grooves. This means the oil film will remain uniform. If you put a worn crank into a different block with new bearings you now have a potential mismatch. The grooves in the old crank can grab the bearings, spin them, and block the oil passage causing catastrophic failure. If you go with “new pistons” from Atlantic you need to test fit them in the bores and measure them per the RAVE. seems the pistons I got during my rebuild were B grade pistons and I had to further bore my sleeves out to get the proper clearance. You should at least run a hone through the cylinders to break the glaze to help seat the new rings.

 

Would a potential solution be to re-use the bearings, or is machining the crankshaft a must? I'll post some pictures of the crank and bearings once I get it apart soon.

 

Re-using the bearings is possible. In my experience the crank bearings experience almost no wear while the rod bearings do see some. In terms of part cost neither is very expensive.

 

I got the pistons out today and here are some photos:
(i put text description between each image that may be easy to miss)

The next two photos are of different sides of one piston. I think there were 1 or 2 that looked like this.




The rest looked like this one.





Where the right con rod connects was the worst looking part of the crank, and the rest look similar to the left side.






The next two are the bearings on that right side.



While the rest looked more similar to this.




and this was the broken piston in my other post that I will be replacing.





So whats next? Are these pistons reusable? How bad is the crank damage? Will it work with the original bearings, or are those too damaged? I'll post photos of the crank bearings when I get the crank out.
If I replace the rod bearings and dont shave the crank, what is the possibility of them slipping? Would this even matter since they dont have holes for lubrication like the main bearings?

 

You haven't said what your expectations are for this engine when you are done. Are you happy with it if it'll just get you the the grocery store for another year before it fails? Do you want to tow a 4 ton trailer at 80mph across the Rockies during a heat wave in the dead of summer? Do you expect to get anther 200K miles out of this process? Your pictures clearly show parts that MUST be replaced - that one piston in particular and that rod bearing for starters. You have what appears to be scoring on that rod journal. Any flaws in the reused parts will immediately transfer to your new fresh parts and jump start the aging process. What decisions you make about that to reuse and what to replace depend on what you expect to have when you get done.

I don't know why LR chose to make honing optional, but that CERTAINLY refers to factory OEM rings. Does that instruction apply if you are using any randomly chosen third party ring? In general, honing is mandatory for new rings. What do you expect a hone to accomplish for you? You are talking about it, so you have seen some info saying it is something to consider - what do you understand it to do for you? A hone can be a necessary step, but might not be a sufficient step.

Share your expectations, it will help get you some less gray, more black and white answers to your questions.

 

I'm hoping to get at least as many miles as if I were to instead drop in the 160K mile 4.0L engine that I am trying to convert to a 4.6. In my mind that is around 100K more miles to be expected, but as you can see my 4.6 terminated itself after 170K.

 

I would not use any that looked like this
The others are usable

I would not reuse the rod bearings, crank looks fine.

 

Without knowing your budget I would recommend downloading the River v8 rebuild manual and blueprint as many components as you can. Did you find out what caused the failure in your bad engine? The piston skirt wear is concerning. The crank as stated looks OK but without seeing it in person can’t tell. Lots of things can be out of round. Anything you are reusing should be checked against the specs in the rebuild manual. Is there a reputable machine shop near you?

 

I'm not quite sure what caused the failure in the bad engine, but I do know it was overheated, probably had a bad head gasket, and was misfiring. There are no reputable machine shops near me that I know of, but there could be some in the nearest larger city that is about 2 hours away. Would a tool like this https://www.harborfreight.com/6-in-d...ngs-63731.html be good for measuring if components are in spec?

 

I noticed some small scratches on the crankshaft. Are these OK?
I




Here is the main bearing and crank wear. I assume the crank wear is fine and that I should replace the main bearings, correct?









Here are some more photos of different pistons. Can they all be reused?