I recently sent a letter to the southern Baptist association recommending the word (bingo) to the newest cuss word but I've not received a reply? My wife is professional player, every night I mean to tell you. SO much kart money WASTED!!!!
I prefer 12 oz on a flat mount, 14 oz. on an angled mount.
No power loss going from 12-14 ounces.
At high rpm, you'd be surprised how little oil is at the bottom of the sump!
We machined a sidecover out of thick clear plastic and viewed the goings on inside the Briggs flathead 20 years ago or more....It really came in handy when I designed the first billet aluminum dippers for the old stock rods. What we found was, anything past an idle, and just about all of the oil is suspended in the air.
I remember back when the flathead was just getting popular (mid 80's maybe?) that when you went to big races, it was common for guys to run 4 ounces or less for qualifying. Glad those days are gone. I'll take the extra couple ounces of oil insurance over any perceived advantage gained by running less.