[Eljaro]

I also do not know why the boiling inside the carbs. The fact is that they are usually cool at the touch after driving, but soak up heat fast and then the boiling starts. I do shut off the fuel supply shortly before turning off the engine and the problem seems to be controlled that way.
Another problem could be the timing. I have to do a few tests with timing to see whether I can keep the engine cooler. I have 20º initial timing, which is a lot, but no problems whatsoever starting the engine. Maybe I could advance the timing more.
Al, How many degrees is your initial timing?