If you are standing at the tail of the plane and looking towards the nose (like a pilot inside the cockpit), then the motor will typically be offset a little to the left of the centerline of the firewall, and the crankshaft should point towards the right. It might also point a little downward. Right thrust and downthrust are typically built in purposely. The 3/8" offset brings the crankshaft back to the centerline at the propellor. I'd recommend you take out the washers.

Peter