A method of assembling a seal in a horizontal split plane gas turbine engine including providing a rotor assembly including a turbine blade assembly defining a forward face and a seal ring extending axially from the forward face. The rotor assembly is positioned extending through a lower compressor casing and a lower turbine casing, the positioning including tilting the rotor assembly at an angle relative to the longitudinal axis for the engine. An upper turbine casing is positioned over the tilted rotor assembly, and the upper and lower turbine casings define a circumferentially extending seal groove. The rotor assembly is moved in an axially forward direction to position the seal ring in axially overlapping relation within the seal groove. The longitudinal axis of the rotor assembly is then aligned with the longitudinal axis of the turbine engine to further position the seal ring within the seal groove.