Vented needle valve for carburetor idle port

Claim 1

A needle valve for use in a carburetor having a throat, a fuel passage, an idle port communicating the fuel passage with the throat, and an internally-threaded bore of greater diameter than the idle port extending between the idle port and the exterior of the carburetor, said needle valve consisting of: an externally-threaded shaft adapted to be adjustably received in the internally-threaded bore of the carburetor with a first end thereof coaxially aligned in proximity with the idle port, a second end of said shaft formed to provide means to permit manual rotation of said shaft to adjust the spacing between said first end and the idle port, lock means adjustably mounted to the external threads of the shaft and adapted to be caused to releasably engage the exterior of the carburetor to permit subsequent inadvertent displacement once the shaft has been adjusted, said shaft having a single, unobstructed, straight, centrally disposed axial air passage covered at its inlet by a disposable air filter of synthetic resinous material, the filter being placed adjacent said inlet whereby adjustment in the threaded location of the shaft requires removal of the filter, the axial air passage extending completely through said shaft and providing direct communication therethrough of ambient atmospheric air and a press-fit pervious cap to retain the filter when in place and which can be removed to accommodate removal of the filter and adjustment to the shaft.