An agricultural harvester includes a chassis and a threshing and separating system carried by the chassis that is configured for threshing and separating grain from gathered crop material. The threshing and separating system includes: a rotor defining a longitudinal axis； a concave at least partially surrounding the rotor； a transition cone defining an infeed to the rotor； and a transition surface connecting the transition cone to the concave and having a conical portion defined about the longitudinal axis and a blended portion connected to the conical portion. The blended portion defines a first end connected to the conical portion and a second end distanced from the first end in a lateral direction. The blended portion defines a substantially conical shape about the longitudinal axis at the first end and approaches a substantially cylindrical shape about the longitudinal axis toward the second end.
