I just changed all of my rod bearings and rod bolts and these are the bearings that I took out. It's the back side of the bearing, the side that contacts the crank journal didn't really look too bad. They all smelt burnt too. I'm just wondering what causes this? Heat?

 

heat?

 

Yeah, that's what I figured as well.

 

Looks like heat damage to me

 

Detonation, what does the front of them look like?

 

Would that be from an oiling problem? Like 17-20PSI?