Abstract: A fuel injector combustion gas seal includes an engine head with an injector bore. A fuel injector having an outer surface and a nozzle outlet is positioned in the injector bore. An elastomeric ring shaped carbon dam made from a first material is mounted at a first location on the outer surface in contact with the engine head. An elastomeric O-ring made from a second material is mounted at a second location on the outer surface in contact with the head. The second location is further away from the nozzle outlet of the fuel injector than the first location. The first material is capable of withstanding temperatures up to about 400.degree. F. for a substantial period of time without undergoing significant degradation.