The chamfer on the rod is there to prevent the rod bushing from galling against the crankweb face. The chamfer always goes towards the crankweb for this reason. Some rods have an oiling hole drilled on the front of the rod so the incoming fuel charge hits the front of the rod forcing the oil into the hole and through the rod bushing. Some rods have holes drilled for lubrication on the bottom and/or bottom front of the big end of the rod as well.