A reciprocating screw injection press has been used to evaluate various accelerator combinations in NR, SBR, EPDM, and NBR. A laboratory mold was used which includes a 75 mm × 125 mm × 2 mm sheet, three molded dumbbells (size Die C), a compression pellet and a Goodrich Flexometer pellet. The total volume of the mold is approximately 85 cm3. Those observations have confirmed that the following relationships exist for high temperature vulcanization, particularly in an injection press. (1) Tensile modulus is reduced at higher curing temperatures for all four polymer systems. (2) In NR and SBR, it is possible to obtain moduli at high temperature comparable to moduli at lower temperatures by increasing the accelerator level while maintaining a constant sulfur concentration. (3) There is a correlation between rheometer cure time (t90) and injection molding cure times. The correlation is good enough to rank the cure time of various stocks, but not good enough to predict cure times. (4) Injection molded stocks consistently exhibit a lower hardness when compared with stocks compression molded at the same temperature. (5) Injection molded dumbbells produce higher ultimate tensile strength than do die-cut specimens. (6) With few exceptions (i.e., very scorchy stocks), the injection moldability of a stock is not dependent upon the vulcanization system used. (7) Even with NR, rather large variations in injection molding times produce only small changes in initial physical properties. The effects of injection molding and it's variables on compression set, dynamic properties, aging characteristics, fatigue life, and ozone resistance remain unanswered and should be the subject of further evaluations.