gm even makes a wrench to do just that... it has the box end wrench and a flat blade built in... so one can to this alone.. feeler in one hand tool in the other,,, or I guess gm thinks its wrong to have a motor in operating temp.. or oil flow that coats the push rod ends and taps... a real world knock or no knock discovered right then... thats a bit tuff to tell with a motor not turning... done my valves four times and there is one that is taping so loud.... so I will find out which one.. it must have a grove that the feeler covers and cant tell... once I find the one,,, I will take it down a few thousands and if the really loud taping stops I'm good... I like it that they all tap a bit... but I got one thats off.. and the rods are all straight...
