The high school where I taught auto mechanics for 20-somethingh years had a see-through single cylinder engine with a tempered glass cylinder. I could "freeze" the motion of the crankshaft, piston, connecting rod, etc. with a delay-flash timing light. Interesting, especially watching the color of the fuel burning as the carburetor mixture was changed. Perfect Circle's "Doctor of Motors" training school had a 216 back in the early 1950's with a quartz insert in one cylinder that allowed students to watch the rings rotate around the piston under a dyno load.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!