hi grumpy,
hey i certainly enjoy tour replies to quite often complex questions , always very well answered with precision & background knowledge , love it , i am also an indentured tradesman. now im sure you will not take this to heart , this is just a little "dig" , but im sure that i was led to believe that it was the valve spring that was responsible for the valve closure , not the rocker or the tappet,
love you grumpy, johnno.

i may have retired but i havent stopped yet, ive got one shed full of woodworking machines & hand tools(my other love, makin sawdust)my othr shed is mechanics tool chests stick &mig welders metal lathe 9 inch swing screw cutting so if icant buy it i make it,i hope im writing this in the right place,thats all i can think of at the moment, cheers & beers