I'm not sure I understand... Been working on bikes and adjusting valves, setting up cams, etc, for a long time, and there is nowhere near 270 degrees of cam movement where no movement of the followers take place. The cam lobes aren't an "all or nothing" proposition. It varies, but all cams have a ramp up and ramp down from full lift to no lift. At any point in this transition area of the ramps, the follower to stem measurement will be affected. We're measuring in thousandths of an inch after all. Small portions of the ramp to either side of center can affect this measurement. TDCC is the place where both valves are in the fully closed position, AND the followers are at their freest, and where you'll get the valve lash measurement that you're after. Depending on the cam duration, overlap, etc, there are a few degrees either side of this where it isn't critical. With the Himalayan it isn't "spot on" critical, but it's still advisable to be decently close to TDC on the compression stroke. And it's nothing close to 270 degrees of freedom, in my experience. Perhaps I misunderstood the statement... But, to answer the earlier question, yes, it does matter which TDC you choose. The piston comes to TDC twice for each cam rotation. At TDCE one or both of the valves will be open to some extent, depending on cam timing. Or at the very least, the followers will not be at their most "relaxed" position, which is where you want them in order to get an accurate valve lash measurement. The above is speaking of a valve train that uses rockers, but the same principle also applies to shim under bucket, direct valve actuation valve trains. The piston needs to be at, or fairly close to TDCC. Get it there and cam timing is pretty much irrelevant.