He covered that he also went through Rockwell test on failed lobes and lifters he covered cam cores where they come from. I wouldn't argue with anyone on this site I am a mechanic not engine builder or machinist. I will say it's the closest to an answer I've seen for DIY mass KIT failures. The crown is so off center their is no way for the lifter to spin in my opinion.
I appreciate you sharing. My issue with his evaluation is that the crown is really only one area that affects rotation to allow burnishing of the cam and lifter contact points. The cam lobe is offset and has taper, which really is driving dynamic force for spinning, and although some crown may help that, I can't swallow that crown differences are the cause of what people report.
What I have seen in a wide variety of failures that have occurred with customers that went on their own, no particular order
1 - Poor prelube with the drippy red stuff or equiv
2 - Excessive turning without oil pressure
3 - Binding anywhere from lifter bore through valve guide
4 - Lifters sticking in bores at assembly
5 - Failure to prelube an engine, or prelubing with starter
6 - Spring pressures not checked or incorrect
7 - Bad start practices - timing off, carb not ready resulting in excessive crank, or immediate shut down after start
8 - Wrong oil
9 - Not following break in procedures
Now I can't argue with the guy finding lifter differences, in fact I applaud him for his time an research, but I haven't seen a single engine that didn't break in nicely and last a long time if each of the things above were addressed, and the ones that came in almost always had one or multiple issues above, so it's hard for me to blame the lifter.
That being said, having good quality parts is hard to argue with.
