Hi Sutts,
Don't forget that the Merlin is liquid coolded : there is plenty of other fluids to drawn out heat to the carb.
I don't know how exactly it was done (if it was) but routing the hot oil out of the engine to the carb on his way to the heat exancher makes sense
Remember that your Lyso is air cooled trought those ugly scoop
c
I hve to say that I hve no remembrance of reading some Spit or 51 pilots pulling any heat carb knob or something like that. Altough they cld hve some sort of electrical heating for take off and landing in a plane like the Mustang.
~S