My thoughts on this after speaking personally to several very experienced builders and posting many times on various forums for other engines I had built for me over the years. I recently had several engines built for me and was convinced after careful consideration to go with hydraulic rollers on all of them. geeteeohguy's post describes builds from 3-5 decades ago. That is the problem. We have all encountered the progressive decline in quality for everything car related over the last few decades, whether tools or parts. A local professional builder/machinist who has assembled thousands of motors locally for 40 years recently stopped assembling them because of the high rate of cam lobe wipe out that they began encountering over the last 10-15 years. Invariably the owners would return griping about the problem but it's not the machinist/builders fault. The quality of the cams and lifters are not what they once were. The technology behind modern hydraulic rollers is what was used on most factory builds for the last 20+ years with no durability issues. Yes there will be clearance issues for the roller components and it may necessitate adapting to it but IMHO its worth it. On my current build I had to use the valve cover spacers and the factory PCV connected to the front of the Q-jet carb but my Holley doesn't have a port in front so I got a longer hose and connected it to the rear of the Holley. You can work around these things. I had built another engine a couple of years ago that I put a hydraulic flat tappet cam in that I haven't installed yet and I just decided to replace it with a hydraulic roller. Just my two cents.
Ah, you have bought into the myth - good for you. I suppose I had better return my Crower flat tappet solid lifter cam then and go all out for that roller set-up. Hmmmm. My machinist and engine builder has been building engines for about 4 decades and still uses and recommends a flat tappet cam on the older engines. He does however NOT use Chinese junk to save money.
What is often overlooked is how radical a cam you use. If you are going for huge lifts requiring mega spring pressures, then a roller cam is probably a better choice. Many of the failures spoken of were many of the early Chinese produced knock-offs at cheap prices. The quality of the metal was poor & soft, thus cam and lifter failures were routine.
Then came along the ZDDP scare, kinda like when they took lead out of gas and all engines that did not have hardened seats were going to sink/eat/burn valves. So a new sub-culture product arose and selling ZDDP additives was introduced for older engines, the focus of which was if you don't have it, you will eat up your flat tappet cam and lifters. Man, what a great defense for all those companies selling cheap & inferior cams that gave out because the reformulated oils took out much of the ZDDP and it was the oils, not the cams or lifters......no, it was the oil! Blame the government, shame on them! So now all those fly-by-night sellers on FleaBay and those wanting to turn a larger profit for cheaper investment had the most perfect defense.
Then they said, so how do we further cover our butts and show to the hi-performance guys that although the reformulated oils are baaaaaad for the old school flat tappet crowd, the new oils can still be used successfully. I know, most modern cars use roller cams and lifters and don't exhibit the failures of cheap Chinese flat tappet cams and we will make that our promotional platform, our focus - flat tappet cams are more likely to fail using reformulated oils without ZDDP while roller cams & lifters rarely do if ever fail without ZDDP.
Of course roller cams and lifters were well under way as being used as standard equipment to reduce friction and parasitic drag so the manufacturers could meet Federal mileage and emissions requirements before the oil was reformulated - but we won't bring this in to our advertising because its the "old school" guys we have to get on board, not the younger mellennium crowd. We will blame the oil and offer a solution - we'll offer the roller cam & lifters as the solution. We'll use fear based tactics, oil ZDDP comparisons, engine dyno results, magazine coverage, internet blogs, and we'll sell "With that much money invested in your engine, can you afford to lose it with an old style flat tappet cam & lifters?"
Yes, tell enough lies enough times and they will buy it. The cam companies are now raking in a huge profit that they could not before because they were being put out of business by inferior, but cheap, mass produced cam & lifters. We'll charge huge $dollars for the set-up, but the old school car culture will pay because it provides peace of mind to the "old school" hot rodders and they have the cash to spend.
But what about needle bearings that can fail in roller lifters and rocker arms? Take it away BearGFR
............ We won't tell people about such things like needle bearings going bad, trunions breaking, rollers falling off lifters and going sideways. No, no, we won't even speak of it, nor the aggressive ramps, or side loading associated with the steep ramps and old school engines that have lifter bores a tad thin for such things. If it breaks, we can't blame the oil of course or our product, we'll blame the age of the 50 plus year old engine and its design - the block was old and fatigued or your engine builder did not know what he was doing and that's what happened. No not the oil and not our product, but the engine or builder. Ya that's it.