How to Set Valve Lash

With all modern engines either net lash or overhead cam hydraulics, there is an art form that is slowly being lost to history. For older engines with independent stud rocker arms, one of the procedures that was necessary and sometimes done incorrectly was the art of setting valve lash. Engines like a small-block Chevy or Ford with mechanical lifters required a clearance between the rocker arm and the valve tip, which was usually set hot. Hydraulic lifters were less critical but still required a preload. Decades ago, this was done with the engine running and open valve covers, making a huge mess when the engine sprayed oil over the entire engine compartment from 16 tiny lawn sprinklers.