Gmerrell

Luke, Your second picture shows the intake lobe and the exhaust lobe to the right. The wear pattern on both lobes is not to abnormal yet. Your biggest concern at this point should be the corresponding tappet bodies. The exhaust tappet body has a wear pattern that is highly unusual. You can see the edges starting to chip. The wear pattern is not normal and is beginning to damage the corresponding lobe. In my opinion you need to visually inspect all the lobes. If they are satisfactory, then replace all the tappet bodies with new or properly overhauled units. Greg Merrell

Camshafts and lifters are not nitrided in most aircraft engines. Lycoming camshafts are carburized and the lifters are chilled iron. The latest Lycoming lifters are hardened tool steel with a DLC coating. Properly reground lifters are as good and possible better than new lifters. It is no coincidence that the lifter that failed was associated with the cylinder that was using excessive oil. The cam and lifter are bathed in hot corrosive blow by gases when the ring seal is compromised. Dry tappet clearance is very important and should be check at assembly time. Properly reground lifters are machined very little. .001-.003 material removal is typical. The dry tappet clearance is effected by other factors such as valve seat grinding depth,crankcase machining,camshaft base circle size.There are many factors that can stack up to effect dry tappet clearance that are way more excessive than reground tappets. Properly reground lifters should meet the new tolerance dimensions of the original manufactured part.