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Ok guys... Here are the facts..
When you have an old engine, espically one that is using oil, and it goes low, you tend to develope knocks.. The knock is a sound emitted from the upper part of the connecting rod slapping the pinon the crankshaft...

There is no knock in a normal engine due to the fact that the impact of combustion is "absored" by the thin layer of oil between the bearing and the rod/crankshaft.
When and engines tolerances between the bearings and rods begin to open, the oil pressure drops, thus inducing wear on the fragile bearings (inserts)..
When the inserts start wearing thin, oil pressure is at an all time low and a knock is heard

When the oil pressure becomes low enough the bearing and rod begin to fuse themselves together, and with the rotating motion of the crankshaft, the bearing spins (knocks the tabs off and rotates)

After spinning, no oil gets to this journal and it's not far from destruction.. Keep driving and the rod/crank sieze together.. You figure the rest.. Can't make it rotate anymore and something has to give - usually the rod that is tossed through the oil pan (if lucky) or through the side of the block...
This my friends is thefacts of a spun bearing, thrown rod and a rod knock.....
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