in dire need of an organic chemistry lesson
Although unlikely, could it possibly be that one (or more) valves got lose from their end and thus jammed the whole area? I guess, no one can tell unless someone tears the beast apart and look inside.If valves have been hit by piston tops, they are likely to bend, and not retract back to their valve seats. So every revolution, the same pistons and valves would be in contact, which is kind of what this felt like, before the tightening up. However, when valves don't return to their seats, the cam followers also don't stay in contact with the heel of the cam lobes, and this can be seen by watching the followers as they rise and fall with cam rotation. Everything looked perfect while I could the crank rotated, and all marks (crankshaft pulley, camshaft pulley, and cam chain sprockets) lined up just right.