An assembly system for assembling a gas turbine engine including a support beam defining a horizontal plane for assembly of engine components along a horizontal axis substantially parallel with the support beam. A forward arm is supported on the support beam for supporting a forward portion of an engine component. An aft arm is supported on the support beam for supporting an aft portion of the engine component. An aft mounting ring is attachable to an aft end of an engine assembly. A forward mounting ring is attachable to a forward end of the engine assembly. A drive is mounted to the aft arm engageable to the aft mounting ring for rotating the engine assembly about the horizontal axis. A roller is supported on the forward arm and engageable to the forward mounting ring to support the first end of the engine assembly during rotation about the horizontal axis. A method is also disclosed.