[olddog]

Originally Posted by DAVID GAGNARD

I'm certainly no engineer, but since the camshaft is turned by the timing chain, turned by the crankshaft, I would think more pressure could be put on the lifter/pushrod/rocker arm than the opposing spring pressure,causing two different amounts of pressure against the pin/roller of the lifter...I would also guess the roller pin is made of some serouis material, and the outside of the lifter (broken piece) that holds the pin in place would be the "weak link" here....the lifter could/would collaspe till it bottoms out and acts as a solid lifter, then there is no "give".
It's possible, might be a stretch, but possible.. I agree, probably a bad lifter, but given those Ford lifters are used in some serouis motors, it's rare to see them fail the way this one did.....Could be some other unkown "thing" contributed to the lifters failure. I wonder what the camshaft lobe looked like????

David

You make a good point. With the ramp rate of the lobe, the force vector on the pin would not be straight up. Therefore if the pin were to flex it should be at some angle, so the break should not have been straight across.