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that the bearings are designed to wear. The material used is quite soft - leadlike, but with a copper substrate. Both this lead and copper are significantly softer than the forged steel crankshaft. There's a reason for this. Longevity. You need to keep in mind that the connecting rod journal on the crankshaft has about 60psi of oil pressure feeding that bearing. The tolerance of the connecting rod bearing to the crankshaft is from 0.0012-0.0018" That's just under two thousandths of an inch. I dont know if you have a micrometer, but you cant really see a gap until around 0.005" and people with poor eyesight dont see a gap until much later. My point, 0.001-0.002" is incredibly tight, but there is clearance.The even distribution of pressure across the surface of the bearing when 3000+ lbs of force is applied to is cushioned my a molecular level bearing - the oil. If the journal runs out of oil, you are in bad shape as at high RPM the rotational forces literally sling the oil out of the journal and the bearing makes contact with the crank's journal. Now, if you are using hard metal bearings, it will wear the crankshaft more than if you used a soft metal.. The potential for crankshaft journal damage is higher with harder bearings. I dont know how to explain this, it just comes to me this way, but having a crankshaft journal worn out-of-round will certainly be worse than the connecting rod bearing being worn. I think this has to do with the oblong end of the crankshaft journal acting like a cutting edge on the bearing as the crank rotates. Any wear on any of these parts will not be good, no doubt, but it seems to me that letting the crank survive and letting the bearing be the sacrificial element would be a really good idea costwise. Bottom line is, I dont see there being any advantage to putting harder bearings in. If it detonates or runs out of oil the damage to the other parts will be just as consequential.. Getting the tolerance on the bearing->journal clearance is critical and starting with a perfectly round conrod journal is the best way to avoid failure. It came to mind also while typing this in, the softer bearing material is likely more pourous so it will hold more oil than a harder denser material. Oil changes are a must really - its the only reason an engine lasts as long as it does. Its amazing to me that as many times I have said it to my wife, she still doesn't check the oil level..
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