Hi George, if it says 140 then yes, that will be the maximum output
In my experience, it's quite likely that 140A will NOT be the maximum output but, rather a figment of the marketing department's imagination. The maximum output is more likely to be at least 10A lower on the spec. panel and it's anyone's guess what it might actually be if measured accurately. I agree with your suggestion to almost ignore where the dial is, and simply find the best setting by trial and error.