For what its worth ,in the process of freeing up my flapper on my 235 with heat I managed to destroy the temperature sensitive spring which probably has a proper name, so I wired up the flap in the closed position so as not to over heat the carb. I noticed no side effects in town but once I hit the highway and started climbing some long grades the throttle response got a little weird as in when shifting gears and taking my foot of the gas peddle the rpm was slower on dropping. I checked under the hood to see if the return spring had fallen off but I found instead a frost like substance at the base of the carb like one might find on air condition fittings when working hard . I rewired my flapper to about half way between open and closed and this seams to have cured the problem until i replaced the spring thingy.
I mentioned this event to some other people who suggested frosting would not occur , but it sure looked like frost to me.
