Valve Lash Adjustment on B9200 Pic

[npalen]

Been putting off checking the valve lash and finally got "arountuit" today. It was interesting in that three of the valves were excessively loose in the neighborhood of 0.025". These three were near the "radiator end" of the engine.
The three farthest from the radiator (at number 1 and 2 cylinders) were a hair snug so loosened them to get the 0.006" feeler gauge to slide easily. I used the mark on the flywheel to verify that the number one and then the number four cylinders were top dead center when adjusting according to the WSM.
I'm wondering why so loose on some and snug on others. The rocker arm jam nuts were all tight. I did check the rocker arm assembly mounting bolts to make sure they were tight.
Looking forward to working the old girl to see if setting the valve lash makes any difference.
Any ideas why so much variation?

 

[npalen]

I posted this thread on another tractor forum and had some interesting feedback from a couple guys including a service tech. I found that using the WSM procedure along with the timing marks on the flywheel didn't work for me.

I ended up using a method the tech suggested of watching the lifters on a given cylinder while turning the crank and seemed to work quite well.