The rod bearings don't look too bad to me, scratches are normal for a used engine.
Place each bearing in its rod and cap and check each one for "bearing spread",
This spread should hold each bearing in its rod and cap snugly, they shouldn't fall out.
If not, try to "pull" each bearing apart with your bare hands to introduce some bearing spread.
Once the bearings fit the rods/caps snugly, install each one in the Engine and plastigauge them.
This should be done with the old bearings, if you replce them, you can compare new to old spec.
This can be done without rings on the pistons, should be lots of youtubes etc. on plastigauging.
Then, remove each main cap, one at a time, and plastigauge each one, then reinstall each one.
I doubt your knocking noise is coming from the crank or bearings, it's probably the wrist pins.
HOW TO CHECK FOR LOOSE WRIST PINS AT HOME:
Hold a piston tightly in one hand and try to move the rod up and down by it's big end.
You won't actuallly be able feel any loseness, but you can
see looseness, if any is present.
Observe the piston and pin closely, while trying to move the rod up/down, and watch the oil.
If the oil residue between the piston and wrist pin moves, the clearance is excessive.
Check this with a piston/rod fresh out of the Engine before cleaning or washing them.
It can take a few tries to get the feel for it and it's very satisfying to actually see it yourself.
In the old days one would have oversize wristpins installed as pistons were expenssive.
Today, parts are cheap, but labor is very expensive, so most replace worn pistons/pins.
Remember, each rod cap belongs on a specefic con. rod so try not to mix them up!!
Sometimes they're numbered, but I've seen 2 Engines that were numbered wrong!!
During final asembly rotate, the Engine fully after each rod is torqued to specefication.
The rotating resistance should increase incremently as each rod is torqued down.
The one I mentioned above, 3&4 caps were mixed up, it could have been very bad!
When # 3 was torqued the Engine would rotate properly, it was time to investigate .
With # 4 cap on # 3 rod it rotated as expected and the same with # 3 cap on #4
A rare situation but a reminder to rotate the Engine continually during assembly.
Some guys actually set everything together and torque everyting all at once.
If you do mix them up I can explain how to match them back together again.
I don't think you showed any pictures of the cylinders, pistons or cyl head?.
This Engine could probably live for years if you put in back together carefully.
Even with loose wrist pins, they rarely fail, but eventually all 4 clack away!!
The rods are press fit, so you need an Engine shop to R&R pistons on rods.
Thanks
Randy
So have a 1988 Dodge Omni with the 2.2 n/a it has the beginnings of piston slap and was smoking/bubbling from the back left corner where the head mates to the block. There wasn't oil in my coolant but my oil looked pretty bad. Before this started I was burning oil. So I started the tear down and got the head and intake/ exhaust manifold off and pistons out of the block. didn't see any damage on the head gasket like breakage between the holes so is the block or head maybe warped? My rod bearings for sure need to be replaced but I can't pull the block to also replace my mains even though they are probably in the same shape as the rod bearings. I've been trying to measure the rod journals and rod bearings to figure out what bearings to get but my numbers are all over the place so l'm not sure if I'm even doing it right as this is my first overhaul. The plan was to strip it to the crank replace the rod bearings and piston rings throw on a new head gasket and send it but I feel like that plan is out the window. I'm using micrometers and telescopic bore gauges from harbor freight. Should I try and continue doing this myself or take it to a shop at this point? I live in apartments and don't have much room plus don't have a hoist or engine stand to pull the block and if leave my car in stands I will get a tow notice it's already happened three times. I was trying to do this myself but at this point I'm not sure if I can as I'm also getting wrapped up in attempting to make sure everything is in spec or not. Mainly my rod journals and rod bolts. It's tempting to just throw everything back together and run it till it blows but I don't feel right doing it that way. It's super frustrating as I started this almost a month ago and my engine is still in pieces. I called a few shops in town and got quoted 2500-2800 for a rebuild. Any advice is welcome as I'm not too sure where to go from here and I don't exactly want to quit but at this point it's tempting to sell it but I'm just frustrated and would probably regret it.
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