I certainly can’t disagree with any of those points. I believe most would agree engines will continue to run for many miles/hours on worn valves before any kind of catastrophic failure or need for overhaul, but there WILL BE a loss of performance. My own personal experience tells me there is a lot at play here: valve and cam geometry, ramp speeds, flat tappet vs. rollers, proper cam break in, ZDDP additives, or as pointed out if they are hydraulic and adjustable at all! The list goes on… I’ve also learned “best practices” say you should re-check and re-adjust particularly after a new or newly rebuild engine after break in- the first one being the most important, then you are probably good to go! Things settle, shift, seat, and find a kind of a happy place. Metals will stretch shrink and warp after a few heat cycles. All of this is normal. In fact that’s why there are clearances designed in! Davesl708 is spot on! After I have checked them for myself and benchmarked I may likely not check them again for a very long time baring any issues. I too was surprised to see Mitsu lists checking every 200 hours. I can see checking after the first 200 then every 1000 or so… Could I get by not checking at all? Sure. But I’m kinda particular about stuff like this when it comes to maintenance. Following scheduled maintenance intervals was engrained into me thanks to the U.S.Navy particularly as an aviation mechanic for so many years.
