I have almost 50k miles on a 5.9 I rebuilt with king bearings. No problem so far knock on wood.

Just went through this yesterday at work helping a coworker looking for some .001 extra clearance bearings for his 351W SBF. Couldn't find anyone who had Clevites or Sealed Power bearings in stock. Even Male/Clevite and Federal Mogul direct. We were able to find a set of King bearings available.

I also just used a set of King bearings in my Son's 99 Dakota with a 360. Sure hope we get over 50,000 on his....

Hot 340, have those bearings been modified or is it some special edition? See attached pictures. Those I bought in 2020 looked like the Summit illustration. Could the modification (?) caused the bearing shell to bend when being "crushed" during assembly?

I’ve built lots of engines and I’m extremely anal on bearing clearances and a crank grind. At one point, my machine shop stopped grinding cranks because of problems with the grinder. The new owner could not work the grinder. I went through 3 grinders before I found a good shop. Like I said, the clearance at the parting line of the rod should be bigger. I’ve never written that number down so I can’t say for sure how much. The big end of the rod starts out perfectly round and will get elongated with use on a stock rod. Then it will need to be resized because it draws in at the parting line and would cause the new bearing to take the same shape and be tight at the parting line. I could see this wear pattern on a new bearing installed in an old out of round rod, but I’m assuming that these rods are new and machined properly. I check everything on resized rods. I check it with a dial bore gauge across the entire bearing. I’ve had rods resized improperly and have a tight spot on one side and big on the other side. In the middle it checked fine. I have an old Sunnen dial bore gauge from a rod machine that I double check my rods when the come back from the machinist.

I’d check the rods first, if this was my rod, and then I’d go to the bearing itself. If the big end was too tight, I don’t think the crush would draw the parting line in but it might. If it was that tight, I doubt it would have lasted this long. I’d look at everything on this one. I’ve never used new Molnar rods before but believe me, I’ll check everything just like I do on a stock resized rod. I’ve got four motors to build using new Molnars at the shop now.

No modifications whatsoever. That's just as they came.. I'd never mod a bearing. Rods are scat, and I've checked all the bores pre assembly..I have the tools as that's my trade👍

Then I say we have a bearing shell problem. That makes the most sense.

these bearings don't look like typical notch from the front, but they look typical on the rear, and the fit in the rod the same as any other. Maybe they defected I don't know.

I've seen more than one new race rod have taper in the rod bearing bore area, smaller I.D. on one end compared to the other side , .0003 or more :

The Glacier Vandervell's are "V" series.

Been using kings for awhile now . What I can offer is this ,
I run a methanol carb and try a you may you are getting some water in the oil . Th HP series hold up well to this .
The only other thing is , at one point I couldn’t get HP and used the XP . There is a clear design difference at the parting line of the thrust bearing of the two different series . The XP is on the left (top) and it failed. I went back to the hp put a notch in it for increased oiling.

You’re saying the xp failed because it didn’t have this notch at the parting line, Could you elaborate on this? Is it a design flaw with xp bearing, Or is it because of the alcohol carb and getting moisture in the oil?

I am saying that I run methanol and the bearings hold up very well.

Re the thrust issue .
I don’t know just an observation. I couldn’t find anything that caused the failure. Have used the HP twice before and No issues. Used the XP once and had an issue. The only visible difference in the bearings is as you see in the pic. The notch I mentioned is not the splayed notch you see . The splayed notch is from King on the HP

Interesting, thanks for the response