I used to work for dresser ind. , got to work on a whole bunch of diff engines they made , mostly complete overhaul . Some of those engines ran for 35 yrs. , with no shut down , they even changed oil in them running .
Never got to work on their v20 , but did work on a v16 in kansas once.
Those engines ran about 200 to 350 rpm , and at that size they should suck the hat of ur head ,I would have thot , never got into that ----------
Dam , i hated grinding poppet valves and bearing scraping ,the reason I BECAME A PLUMBER ,''was a shi--- job tho !----------LOL