I'd be reluctant to put Propane into a crankcase- - - - -launching a set of valve covers into low earth orbit would be a distinct possibility. I've seen a severely flooded MOPAR 361 engine develop enough fumes in the crankcase to bulge the valve covers and oil pan when a spark plug finally dried out enough to fire. There was a hole burned in one piston, and the crankcase vapors exploded. I felt the breeze as the oil filler cap went past my left ear. We never found the filler cap, and my ears stopped ringing after about 15 minutes!
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!