Good analysis. And the flex occurs under full load, (with the valve wide open
which is NOT where you measure the lash.
BTW it is a bit different for the B30 which has identical port layout, not
symmetrical as the B20. B30 also has all big bearing journals on the cam,
where the B20 has smaller bearings in the rear, which is probably of little
consequence.

But it seems to me that if you adjust the valve lash with both valves closed
you are probably in pretty good shape. And a difference of 0.001" lash in a
valve that opens 0.400" or more is pretty small. I am personally more
concerned with getting the valves (especially the exhausts) tightly shut than
I am about getting that last thou of lift. I used to set B30 valves at 0.018"
as opposed to the factory manual's recommendation of 0.021" and in less than
10,000 miles had cracked 5 of the 6 exhaust valves in the seating area. I
attribute this to overheating because of insufficient seat pressure to conduct
the heat away from the valve heads through the seat contact. The valve seats
were pretty much OK.
--
George Downs Bartlesville, Heart of the USA!