Special screw tap for engine guide pipe

The utility model discloses a special screw tap for an engine guide pipe. The special screw tap for the engine guide pipe comprises a screw tap work part, a screw tap handle and a fixing square head which are formed integrally, wherein the fixing square head is arranged at one end of the screw tap handle, the screw tap work part is arranged at the other end of the screw tap handle, the axes of the screw tap work part, the screw tap handle and the fixing square head are on the same straight line, three sets of screw tap blades are evenly arranged on the periphery of the screw tap work part, a chip discharging groove is formed between every two adjacent sets of screw tap blades, and each set of screw tap blade is provided with a double-head rightwards spiral thread different in depth. The overall stability is good. The machining of a double-head rightwards spiral thread groove in the wall of an inner hole of the engine guide pipe is realized, the length of a front guide part of each screw tap blade is 5+/-0.5 mm, and the special screw tap for the engine guide pipe is not only good in guide function but also long in service life.