Hi guys
The push configuration will not have any effect on the engine mechanically. The prop shaft / cylinder, is locked in the front housing, and cannot move. In fact the front housing expands more than the cylinder and moves the gears farther apart if anything. This is with the exception of the older 60SP engines which were locked against the front bearing and could move some, but not enough to ruin gears. The most pressure you could put against the gears in this situation would be the weight of the aircraft. This is nothing compared to the pressure placed against the gears in a tight engine. The only thing that might be damaged in a tight situation would be the two small crank shaft bearings. You would cause more damage if you ran the engine in very cold weather, which could cause insufficient thermal expansion. The only concern I would have in a push situation would be the flow of direct cooling air, which may be lacking in this situation, nothing els.

Otto Kudrna