BRIAN - I saw that, but figured it was the angle the pic was taken at with the valve just slightly open. Warped valve would leak a LOT of compression, surprised the engine ran at all.
The best way to prevent that is to let the engine idle for a minimum of 3 to 5 minutes before shutting the engine off. That warning used to be in EVERY operator's manual for every tractor, car, truck, self-propelled combine, baler, etc. BUT I guess today they have to spend more time explaining the controls for the radio, Blue Tooth, heater & A/C, etc. so things like not shutting off a blisteringly hot engine don't matter.
I remember Dad's Super M-TA used to pop and back-fire when hot when coasted down the road in 5th gear, like when returning from the other farm a half mile away, go from wide open to low throttle and you were sure to get 3-4 Pop's that I'm surprised didn't split the muffler wide open... then if you didn't let it idle another 2-3 minutes, it would pop again and spin the engine backwards, which drives the oil pump backwards, so no oiling, hard on the T/A sprag, loads the oil bath air cleaner up with gas vapor, etc... and also would warp the valves once cooler air drifted down into the muffler & exh manifold. So much for the idea that low compression engines can't detonate, ping, etc. even on good old leaded regular gas vintage 1964.
