Posted for Rick Lafford <gliderguy89@earthlink.net>:

 I believe that reading the available literature will bring one to believe
that the "shock-cooling/cracked head" OWT goes back to the days when cylinders
were run until wearout. The problem is that the metal fatigues over some
number of thermal cycles. If the cylinders are junked at overhaul I suspect
you would seldom see a cracked head if the engine was operated within the
recommended CHT range.
 
 As for not allowing the prop to drive the engine, I remember reading that the
geared radials didn't like it one bit but the problems created were gearbox
related.
 
 Rick Lafford (Legacy someday)
 Dansville, NY