The 350 under my hood has (according to the previous owner) a Crane Energizer 272 hydraulic cam. Lately, I have noticed what sounds like a lifter tapping (but this is just a guess, it is difficult to hear over the noise of the gear drive) I talked to the previous owner about the history of this truck, and he told me that he "adjusted the valve lash" on this engine when he put the camshaft in. My questions: 1) I was unaware that there was any valve lash adjustment on a hydraulic setup. Is it true that the valve clearance needs to be set, and, if so, what should it be set to? 2) A semi-reliable source told me that I should "expect valve noise from any engine that has a long-duration camshaft" I find this hard to believe, and, considering the source, I must ask you guys: What type of noise (if any) should a healthy vavle train be making?