Jeep Strokers

About 40 mins into breaking in my new 4.6 stroker, right after the first oil change, took it out for a spin and it felt awesome for all of about 4 minutes. I might've been a bit hard on it, accelerating gradually to 3000rpm and using engine breaking to slow back down a few times.
Then disaster struck, out of nowhere the thing starting knocking and screeching, I quickly shut it off and pulled over, we cranked it a few times and noticed a squeak each time the engine makes a rotation, with or without belt installed.
Towed home and pulled valve cover, cranked and found all pushrods spinning nicely, the squeak synced up with cyl 4 exh valve opening but now I have reason to believe thats just coincidence.

I dropped the oil pan today to find metal shrapnel in the bottom. Inspected and noticed rod end on cylinder 3 discoloured, removed cap and found bearing completely destroyed, crank journal scratched up pretty bad, oil galley is packed with bearing material.
These were new Scat rods, I had my new scat crank journals re-ground for .01” undersized bearings because the crank came with journals ground too small to begin with. A reputable local shop did that for me and micd all bearing clearances and gave me the green light to put it all together. I was diligent about cleaning out all the oil galleys including the crank.

Im really not sure how this could have happened, either way the engines coming back out, full tear down to clean the metal out, and we’ll go from there, most of my $$$ parts should be salvageable. Huge bummer.

Some photos

What is that round spot in the middle of the crank bearing journal? Should that be an oil hole?

mpgMike wrote: ↑December 13th, 2025, 8:33 pm What is that round spot in the middle of the crank bearing journal? Should that be an oil hole?

Yeah that's an oil hole that's been welded shut by bearing material and lots of heat.
Besides oil starvation (which I don't think applies here), the only reason this rod bearing failure can happen during engine break in is the rod bearing clearances being too tight.

We do major engine work here at my shop. I have found we HAVE to blueprint everything. In fact, doing a 350 small block Chevy for an '82 truck, we went through 4 sets of cam bearings before getting 5 usable bearings! On a 6.2 GM LS rebuild, similar situation where the bearings weren't what was on the box. Too many parts are now made in China, and the quality has dropped dramatically. Even if using "reputable" parts, blueprinting ensures the machine shop did good work as well (an issue with 0.010" under rod throws -- except for one that was 0.020"??). Blueprinting is no longer an up-sell, it's just part of every build now.