NetMaster....

....just as a reference, this is a good running used K&B .61 engine. See how the rod
is barely touching the backplate. The machining marks aren't even worn off the
rod. I would make 100% sure the bearings are seated, then if the rod was rubbing
too hard on the backplate....I'd take a few thousandths off the backplate on the
flat plate....with some emery paper, or make a thicker gasket.

When the engine is running, the thrust from the propeller pulls the crank forward.
It shouldn't be rubbing very hard against the back plate. When you shove the crank
rearwards with the electric starter, it may well rub, but it shouldn't be rubbing all
the time.

FBD.