Checking main / rod bearings - what to look for?
Checking main / rod bearings - what to look for? I'm pulling my motor shortly to check out the bottom end to see if it needs to be freshened or not. Has about 200 or so passes on it. I plan to do a leakdown before disassembly to check the rings and I'm going to pull the rod / main caps to look at the bearings. Question is, what is normal bearing wear and what is a sign of needed replacement? I know any copper showing is definitely bad, but what else? Are there any good pics out there showing normal and abnormal bearing wear?
Thanks!
Thanks!
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I dont feel this is "technically" a good advanced topic but....
http://www.bobistheoilguy.com/bearin...aranalysis.htm
http://www.sacskyranch.com/eng219.htm
http://www.hadmac.com/technical_info.htm
Google searches do wonders.
Now if you wanted to talk about the construction of bearings, determining/designing bearing clearances, Hydrodynamic lubrication w/ pressurized feed, etc.. that would be a better topic.
http://www.bobistheoilguy.com/bearin...aranalysis.htm
http://www.sacskyranch.com/eng219.htm
http://www.hadmac.com/technical_info.htm
Google searches do wonders.
Now if you wanted to talk about the construction of bearings, determining/designing bearing clearances, Hydrodynamic lubrication w/ pressurized feed, etc.. that would be a better topic.
Attached is what "bad" rod bearings look like. 
These came out of my Fiero. I simply replaced them with a new set, and behold, 10 more psi of oil pressure and my knock was gone. 
Car's still running fine. 
One thing I found with my LS1 motor was that the mains had egged a bit. So when I built my 383, I left the bores alone (500 miles since the 347 build), but had a line hone done. I suppose it depends on how far you want to go with it... if you're just checking for wear and replacing (like I did with the Fiero), or if you're measuring actual clearances and want to tighten things up to spec. But you can simply replace bearings and go, if you like. Just be sure to replace with the same spec (but I'd be careful on the thrust bearing, as those are usually fit based on the crank fore/aft clearance).
These came out of my Fiero. I simply replaced them with a new set, and behold, 10 more psi of oil pressure and my knock was gone. Car's still running fine. One thing I found with my LS1 motor was that the mains had egged a bit. So when I built my 383, I left the bores alone (500 miles since the 347 build), but had a line hone done. I suppose it depends on how far you want to go with it... if you're just checking for wear and replacing (like I did with the Fiero), or if you're measuring actual clearances and want to tighten things up to spec. But you can simply replace bearings and go, if you like. Just be sure to replace with the same spec (but I'd be careful on the thrust bearing, as those are usually fit based on the crank fore/aft clearance).
