Quote:
Originally Posted by nkaminar
Regarding a hit and miss engine. The intake valve is opened by the suction in the cylinder against a weak spring. When the flyball governor senses that the engine is running too fast, it will open the exhaust valve and turn off the magneto. The engine coasts with air being sucked in and pushed out with the open exhaust valve. The intake valve will not open because there is not enough suction. When the flyball governor senses that the engine has slowed down it will allow the exhaust valve to close and a fuel/air charge will be sucked into the engine and ignited by the now working magneto. The magneto is not like a modern one but operates by moving a magnet in a linear motion.
Fascinating engines. It seems like they run forever.
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Got that part mostly right. The rest of the story. The next 4 strokes the exhaust valve for those not familiar with the 8 cycle Aermotor is open due to the cam profile. The cam gear is 4 times the crank gear, (of course in the 4 cycle engine it is 2 times the crank gear) the last 4 cycles - down, up, down, up with the exhaust valve open then back to intake, compression, power and exhaust. Interesting point is that the exhaust exits back toward the exhaust valve cage for more cooling.
John