Abstract: An adjustable idle needle valve assembly for an internal combustion engine carburetor includes an air bleed threaded needle valve mounted on a plug for a tubular metal housing, an insulating fiberglass sleeve in the housing and an electric needle valve heater coil within the insulating sleeve. The heater coil extends between the needle valve mounting plug and an outer air inlet plug for the tubular metal housing. An air-conducting shield tube extends between the plugs for isolating the flow of bleed air from the insulating sleeve, particularly when the outer plug is connected to a liquid vapor trap.