We have a 67 MGB in the shop that was making a bigger than normal valve clatter, so we removed the camshaft to investigate and found seriously worn lobes and lifters. Once the tappets get pitted, it’s all over, as they will steadily grind away the lobes of the cam and rob performance and ultimately start to make a lot of noise. In the video below, you can see the extent of the wear. While this video features MGB engine parts, all classic British cars are vulnerable to this problem.
Modern oil no longer has ZDDP added, apparently since late model roller bearings don’t need it and because catalytic converters are damaged by it (thanks Bob for the heads up) and so all classic cars are out of luck. Apparently the zinc makes a protective coating that will reduce wear to the valve train. We are offering zinc additive in a four ounce bottle you should add after every oil change. It’s cheap insurance, and after seeing this camshaft, we are now believers! You can click here to order some zinc for your engine, or check out “for sale/accessories,” where you can order zinc and other good stuff. And some racing oils also have zinc added, check the label!