Engine builder's, cam bearing surface ???

The MM quote is right. But, since the cam bearings are fed very well, and there's not too much pressure on them, and it has five bearings to take that pressure- I never felt bad about carving on them. You DO NOT hone them. Honing stones break down under use. As they break down, if the surface being cut is hard,the abrasive goes into the oil as it's honed. If it's soft, the abrasive embeds in the material. So those bearings have crap in them. That's why cam bearing knives were invented when cams started being supported by bearings. I use a single edge razor blade to do mine. Cam should turn by hand (like using your fingers).