At my school, we build and dyno 6-8 flat tappet cam engines a year. In the last 20 years we have lost one cam on the dyno I mentioned in a previous post. So that is a minimum of 120 up to 160 engines. Most are mild builds or restoration builds. I would guess most were in the 250-400 HP range. But several had pretty hot cams and made over 500 HP. I have not heard back from any other students about failed cams once in their cars on the street or track. I would say about 25% of the students have come back with their cars to show off or I have seen them at Cars and Coffee. No complaints. My personal 462 Pontiac built last year with an Ultradyne flat tappet cam ran for several hours on the dyno. 48 power pulls trying to get the pair of dumb AFB's tuned and running great. I put about 1700 street miles on it last year. Flat tappet solid. Adjusted the valves once on the dyno. Valve covers have not been off since.
I will say we have had 3 engines at the school with roller lifter failure on the dyno. One was a Morel lifter that would never oil. Another was a Lunnati that broke a tie bar. The third was a Isky that lost a roller wheel and tore up everything in a BBC. So roller lifters. solid or hydraulic are not the magic pill IMO. They do make lots more power and are necessary in real high power builds. But they can fail at about the same rate unfortunately.
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