Flat-tappet camshaft failure is a common topic today, and the lack of adequate levels of high-pressure anti-wear additives present in modern-spec oil is most likely the cause. This lifter was sourced during the mid-’80s, and we always used top-quality oil, yet it’s quite obvious that the face was beginning to dimple. While this type of wear can be considered normal in a high-mileage engine, our 455 H.O. had about 10,000 miles on it since the last rebuild. It was only a matter of time before the lifter failed completely.