Ok I just remembered that other than some time holding spanners for my Dad on the farm pre ten yo, the earliest experience I had with engines was my neighbours owned the local garage, and they had a '32 A model ford they used as a scrub-basher....being a side valve, the valve lash was adjusted if I recall (or am making up as I go 'long), behind a side-plate on the block....tappet adjustment was above the cam followers/lifters...
, so at the time the two were kind of closely associated, as they were if I recall on the side valve Beezas M20/21, I only had one WM20 for a short time and never had it running.
A reasonably easy case for not giving thought to some things