Recently I discovered that my roadster pickup drag car had worn throttle shaft bores. This caused the throttle plates to be loose and leak air into the fuel / air stream. That created an erratic idle that could not be cured by adjusting the idle mixture screws or the curb idle screw. A search on the internet failed to find any good description on how to properly fix the problem. So this article addresses the problem. The carburetors in question are the Autolite 2150 series two barrels. They are a good carburetor with many advantages over other more popular aftermarket brands. Additionally, they are abundant in many bore sizes and available relatively cheaply. The steps outlined in this series apply to other brands of carburetors also. The kit I ordered is from HENKYO. It consists of a 7/16” reamer on a 3/8” shaft body. The kit also includes eight knurled bronze bushings. I found it online for about forty bucks. It was my plan to use the reamer in reverse. That is, insert the 3/8” shaft body into the worn shaft hole to align the reamer and then, by turning the reamer backwards (counter-clockwise) I could ream out the shaft bore on center with the original shaft axis. Well that turned out to be not as easy as hoped for as the reamer would not cut when held backwards and turned in reverse. More on that later… Placing the carbs on a bench upside down gives access to the throttle plate screws. On these carbs they are #6 screws with extra fine threads. Some brands of carbs peen the threads of these screws; some crimp them; others use trocho-centric (vibration-proof) screws. It may be necessary to grind down the protruding thread with a Dremel tool before removal. ONE CAVEAT HERE: THE SCREWS HAVE VERY SHORT HEX HEADS. Be very careful not to strip them out! They were tightly secured in the shafts and required that I modify a 3/16” six-point socket by grinding it down to eliminate the slight lead-in chamfer on the socket. Leaving the chamfer in place did not provide enough hex head purchase to loosen the screws (I tried several brands) and the hex will round over before reaching breakaway torque. Mark the location of each plate. Once the throttle plates are removed the throttle shaft is ready to be removed. Almost. It will be necessary on an Autolite / Motorcraft 2150 carb to disengage the part throttle air metering rod cam from the shaft before the shaft will come all the way out. 2100 Series carbs do not have this feature (often referred to by carb technicians as “crowd control”).