I recently rebuilt my 5.0 because the number 5 rod turned a bearing unexpectantly. When I pulled the oil pan off the first thing I noticed was several large flakes of aluminum stuck to the pickup. These were way to large to come from the bearing. I didn't have to look hard to see that the flakes were actually burrs that had broken off from a machine's surface right below the oil pan. All I had to do was to gently touch it and pieces easily fell off. Be careful because they are shape as razors.
When I shook each rod, number 5 was very loose. I pulled the cap off and there wasnt much left off the bearing halfs. They had actually worn so bad they turned and piled up on each other which accounted for the terrible sheak it made as it failed. The other bearings looked like they had extra aluminum smeared on them. I never saw this before and I knew it could not have happened from the pieces I found in my oil pan because they could never make it past the oil filter.
When I took the oil pump off I found the problem. The machine surface had not been deburred either. When I pulled the valve lash adjusted out of their bores and tested each plunger everyone of the ones on the drivers side of the engine were stiff. I actually had one fall apart in my hands. The otherside had three that were stiff. The one that fell apart had shiney grit in it which In assuming was aluminum.
When I took the variable cam adjusters off and inspected their filters both driver side filters were clogged completely with aluminum from the oil pump.
. Atleast I can say that this engine is very easy to rebuild. I had a machine shop turn the crank. I used King racing bearing for both rods and mains and sized the clearance for 0.001"/inch of diameter which required me to go to a heavy racing oil.
The engine runs great as before and I'm going to be bracket racing it again real soon.
I thought I would just throw that out there anyone who was swapping cams to make sure they check the cam filters. If you find aluminum pull the oil pump and deburr the surfaces so you want have the same problem I did.
I read somewhere that losing a rod bearing was pretty rare with these engines but it said that if you do lose one it will probably be number five. If you study how the oil flows from the oil pump it makes sense.
I'm new to this forum and have enjoyed reading the threads I've looked at so far. I think I need a new cam positioning sensor o-ring because every one in a while merging on to the interstate or hitting the base of a bridge while I'm going down hill, I will suddenly have a multiple misfire situation. I've never been able to figure out why this happens but because you folks never give up until you get to the bottom of a problem I think I now have the fix. It's really a dangerous thing to happen while merging. I never heard anyone say that they turn the key off one position then turn it back on with the clutch out. Dont do this with an automatic. Usually it clears up the first time but it has taken up to three times in fast succession. It's better than hitting the emergency lane and stopping. Just dont do this if you have an automatic.

 

Interesting post, thank you for the information.