Camshaft wear - How to identify worm camshafts?
It is easy to tell if a cam is worn out without removing the engine or the need for close inspection.
When the tappets become worn (normally 60,000 - 80,000 miles) the tappet base becomes concave (dished), so that when the camshaft rotates through 360 deg. the tappet will only ride on the edges of the camshaft and only make contact in the centre when it goes over the (worn to shape) cam lobe. This has the effect of causing the camshaft to be brown in appearance and shiny on the edges. The cam in a Rover V8 is hydraulic in design, which means when it is manufactured the lobe is cut at a slight angle so that it rotates the tappets, this is essential for them to fill with oil. Even when the lobes still look intact, if the cam is starting to discolour, it is well on the way out. It is important to change the cam before it starts to wear away quickly because the metal particles produced will rapidly cause further wear in the crank by becoming embedded in the white metal bearings and softer aluminum rockers, thus causing further metal particles to be produced. Replacing the camshaft and tappets before they get bad will greatly extend engine performance and long life.
Longer engine life, increased engine efficiency, smooth idle and good power, cannot be expected from camshafts that look like either camshaft b or c shown in these images (and it is not an uncommon sight).
Camshaft b is showing all the discolorations mentioned, the Camshaft lobes shown are all becoming rounded on the shoulders, it's clearly been bad for quite some time, and will have caused considerable harm to the engine already, not to mention the engine's performance and efficiency.