Truck Repair: n14 celect, blown head gasket, pitch changes

Question
First are tappets orintation big hole to exhaust side of engine? also when setting injector clearence, tighten hand tight and back out 2 flats, is this using only fingers and not a wrench? I have set them to 25 inch pounds and out 2 flats and have slight valve noise.
Also before replacing injectors have had a fairly loud knocking noise. It changes pitch with acceleration and is not a constant noise but will subside to a lower pitch and go away when under full load (slowing on a large hill). It makes no noise at idle or in lower gears at all. It makes this noise like it would be a frozen lifter on a gas engine but pitch changes under condition from high pitch chirping to a solid knock in time with the valves.
I replaced all injectors because a mechanic told me it was an injector but it still remains. I have noticed no power loss or smoking. Any ideas would be appreciated.

Answer
On the Celect,you adjust valves & inj on same cyl.The mark A is now 1-6,B is 2-5, & C is 3-4.Valves are Int 0.014 & Exhaust is 0.027.The injector you hand tighten screw until injector plunger bottoms out.Back screw out 2 flats,ie turn corner of lock nut to align with the rivet in the rocker lever(pushtube side),then back out screw two "corners" then tighten the jam nut down.Adjust the Injector first,then the valves.
Might have a blown head gasket.There are no lifters in the engine.They have solid roller camfollowers & a pushtubes to activate injectors & valves.