01-05-2021, 07:09 PM
(11-03-2020, 08:33 PM)Dave Mann Wrote: I'll upset the apple cart, since getting my first Seven in 1962 and a copy of LM Williams Specials book I have always set the tappets at 0.004" cold. After an article on tappet clearances in the PWA7club magazine last year I took one of the Sevens out on a blistering hot day up a long steep hill grinding away in bottom, at the top I quickly stopped and dropped (literally) the tappet cover off and checked the exhaust valve tappet clearances. All were an easy 0.002". Any engine rebuild includes grinding out the wear dimple in the tappet screw. I had to wait a while before I could refit the tappet cover.
old thread, but just out searching...
Is the point here that 6 and 7 thou gives an adequate safety margin, but that as long as the valves ARE physically released, then the engine will be more efficient if that release is as small as possible? i.e. Dave's "easy 0.002" in extreme circs shows that the cold 4 is ok for the rigorous?