Abstract: A glow plug for internal combustion engines, the plug including a plug barrel, an electric heater for igniting the fuel, and a device for the metered injection of liquid fuel into the glow plug. The plug includes a centrally positioned heating pin in a pasageway through which the metered fuel passes, the heating pin including a thickened portion to define a valve. A chamber is provided in the glow plug barrel and is heated by the electric heater for evaporating the injected liquid fuel. The barrel includes a tube around the heating pin tip to provide a mixing chamber that contains concentrically arranged bores that extend into the mixing chamber and are connected to an air supply line in the vicinity of the opposite end of the plug barrel to permit air and evaporated fuel to mix to give improved combustion.