My XJ stroker is about 5 years old, but it's not a daily driver, and the last few years it's been trailered to all the runs, though it can see plenty of miles on various trips. It gets driven to work and around town some, but not all that many miles overall. I haven't followed what problems folks have been having with the Crane cam, what is it?
Hmm well thats a loaded question, But here is my opinion.
the failure is either the cam or the lifter that gos soft and eats its self up!!!!!!!!
What cause the failure is the new oil recipe thats bad for flat tappet cams, AND the poor quality control on some lifters and even possible the cams,....and the after market narrower lobe then the factory used.............and spring pressure.........the more you got the shorter it life will be.
Cam savers lifter, GM's M.O.A thats my recamendation for life.
O and its not just crane that has had these kind of failures.
At the time, I was told not to use the stock springs with this cam unless the spring seats in the head were machined down slightly, but the Mopar Performance springs were fine.
As far as rpm, it's an automatic, so it will rarely see more than 4500 rpm. But, if I'm in low range and at top speed while racing, or bounce it off the rev limiter on a bad ass climb or in the dunes, it needs to hold up. Won't happen often, or at all, but it needs to be able to handle it.