I had the whole stud/nut on my air cleaner come loose and go down the drain during a race once. I had about 4 laps to go, running 3rd. And lost a cylinder. When we took it appart, you could see the imprint of the threads on the piston and valves, It ate the head up and killed the valve seats.... you got damn lucky! it was a 4$ part. Ended up costing probably 12-1500$ plus what $ i could have got for a top 3 finish!