Quote:
Originally Posted by HWYSTR455
My imagination or the one piston pic in post 75 looks like a valve contacted the eyebrow?
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I saw that too? The Impression of the valve head slightly off-register with the valve relief.
These are not domed pistons, they are dished. If the piston were to come into contact with cylinder head, the perimeter of the piston would smack quench area (flats) surrounding the chamber with plenty of clearance for the plug electrode. Also, if the pistons hit the three plugs and closed their gaps, where are the witness marks in the tops of the corresponding pistons.
The phraseology of spun bearing is just that. The bearing turned (spun) in its journal and the tang on the back of the bearing causes the bearing clearance to close up and wedge the bearing tight against the crank. The bearing and crank heat up wedging eve more tightly and in conjunction with oil supply due to the bearing advancing and restriction or even fully covering the oil hole, the engine seizes. The the inertia of the camshaft turning (slack and free play in the rollers) while the crank stops abruptly sheered the corner of the keyway off.
Also, there is a lot more metal in the oil pan than a chip from the corner of the keyway would create, plus it would still be pretty much intact as the the motor was stopped dead in its tracks when it would have dropped.