| number of miles still on them when I pull them out but they always show wear and stress. Nissan bearings are still, in my professional opinion, the best bearings for these motors. Ive seen Clevite, ACL, and King bearings that have come out of these motors with less miles than what I run them through and they all show significant signs of babbit fatigue; lots of small cracks in the babbit surface. The Nissan bearings hold up significantly better with less wear and much less show of fatigue. This time around, since the motor was out of the car, I took the opportunity to measure each and every journal on the crankshaft to see what kind of wear the crank has experienced. I have an 8.5X11 sheet here that I wrote all the dimensions down on when I first machined the crank back in 2004. There are no measurable differences in the roundness and squareness of the journals compared to before - every one of them are all within 0.0002 (two-ten thousandths of an inch) in roundness and squareness, measured at 4 points on each journal. Most of them are all within 0.0001". The #1 reason I've been so anal about bearings is because of the 60+ hours I put into the crankshaft itself. I know the rod bearings are the weakest point of the bottom end and I've seen them fail time and time again on many other high HP cars. With that knowledge I took it upon myself to swap in new bearings every 15K miles to save myself the emotional agony of losing that rotating piece of artwork that took me a ton of time to produce. :)
Crank shown here was a bad crank that I used to nail down the steps I would use to machine the final crank. But you can see the "crankinator" fixture I built to do the actual machine work.
 
I drive the car pretty hard - like it was built to be driven. With that plus the power/torque it makes, there's bound to be additional wear on the bearings that were designed to be used on a 300HP engine. The approach has worked thus far and I dont see any reason to change up. The main bearings have always looked exceptionally good each time but I've changed them anyways. The rod bearings are what always take the abuse but for $120 worth of new bearings and 4-6 hours spent to replace them, I'm more than happy to do that to keep from spending a few thousand dollars in repairs if one of them lets loose. Not to mention, I dont have the equipment at my disposal anymore to machine out and balance a new crank like that.
Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the
tailor.
Albert Einstein
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