So here's what I read in face book today (people complain about 312 Fords)
When rebuilding an LS, you often hear, “Never look at the cam bearings!” That’s mainly because pretty much every junkyard LS engine has what looks to be wiped-out cam bearings. Steeped in much mystery and internet rumor, LS cam bearings have long been a sore spot for DIY builders, but why? The issues go much further than the looks of a stock bearing.The primary issue when rebuilding an LS or LT engine is that when you pull the cam, the bearings look like toast. Every bearing
looks worn, often showing copper. In any other engine, this would be a guaranteed sign of failed bearings, likely due to oiling issues. However, this is not the case with LS and LTs, as GM used a different procedure for these engines, and this is actually considered normal.On the cam journals, just a slight amount of core shift in the block's casting can cause misalignment for the camshaft. You don’t want the cam bearing journals to be offset even a thousandth of an inch, which can cause hot spots and premature failure. However, because the LS uses 3 different bearing sizes, align-boring the block is much more difficult. GM decided that instead of trying to line bore every block, they would instead use clinch-style bearings and align-hone the bearings themselves after they were installed, yielding a perfect align bore.
