The locking of the clearance is done solely by the two 14mm nuts. The large nut turns the valve, rotating the valve helps find the tightest clearance spot as the valve rotates, that is where the clearance is best measured. If the valve clearance is set in the loose rotation spot, the clearance will be too tight when it turns to the tight rotation spot. Put a feeler gauge in to take up all of the clearance on any closed valve and feel the difference in clearance while rotating that valve with the big nut.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer