Abstract: Disclosed is a preform molding system having a cavity assembly having an end forming portion and a body forming portion. A cooling chamber is defined between the cavity assembly and a surrounding structure. An outside surface of the end forming portion and an outside surface of the body forming portion are spaced apart from the surrounding structure, and, in operation, are engulfed in a flow of cooling fluid within the cooling chamber. Also disclosed is a preform mold stack having a cavity assembly that has end and body forming portions for molding a preform. An annular cooling chamber is defined at least in part by the cavity assembly, and is for cooling a preform molded in the cavity assembly. The annular cooling chamber extends in a longitudinal direction along the length of the end and body forming portions of the cavity assembly.