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So it looks like the yellow circle in the pic was a crankcase vent.
WJPearce, I want to know what you think seeing as you are a fountain of knowledge on engines.
I think the air/fuel valve could have opened for less than 250 degrees, since it could be a very fuel-rich mixture. Since these engines had 1100+ mm Hg (21+ psi / 73+ inHg) of boost, it would not take long to charge the cylinder. But I still don't understand why it would close 82 degrees after the other intake valve.
Russian engine Klimov M-105PF, VK-107A ...
1100 milimetres Hg ... is circa 43.3 in Hg ... or (british equivalent) boost pressure +6.574 P.S.I.