Rocker Arm Stud needs repacing ?

[Dibdob62]

Took the truck out at the weekend and it started knocking, Found the problem when I got home. When I took the rocker cover off one in the rockers was sitting at an angle, Pulled it apart and found this

The rocker stud has a deep grove worn into it and the top of the valve stem is pitted.


I plan to replace the push rod, rocker stud and fit a new rocker kit.


Questions 1, What's the easiest way to replace the rocker stud ?

I've seen some videos with screw in studs but can that be done safely with the head still in the truck (I really don't want to have to take the head off if I don't have to)

Question 2, Will the valve stem top be ok as is or should I try to smooth and polish it ?