ORIGINAL: BarracudaHockey
Not sure whats hearsay. They are designed to expand when they get hot, if the top doesn't expand then the piston gets pinched on every stroke.
Very few engines are so tight that they'll pinch when flipped over quickly with a glow plug installed. A running engine will not have the cylinder at ambient temperature even when running rich.
"Downunder" has already tested, and disproved, the danger of running an ABC rich in a another long thread on this forum....