Mystery wing

The Fox is a 1974 vintage which was made available in a .29 or a .36. This engine was a total flop for Fox as it's initial tendency was for slow combat for bushed engines. Once again, Duke fumbled the ball and the rules changed and he had to redesign them to get rid of them. While I don't remember the entire backstory, this occurred more than once. The .29 says .29 on the engine lug while the .36 offers no displacement designation. The .36 utilized the .36X piston sleeve and rod. While it went like gangbusters in the .36X, it was more turdlike in this variation. I have seen some pretty good runners and I do like these but they do lack the uumph the X series offered. In addition, they can shake like nobody's business.

             If you think that the engine has no run time on it, I would first open it up and clean it out. Fox offered metal chips and pieces ( Free of charge) in many of these engines. Usually where machining was done, there's lips and burrs just waiting to fall off so these do require a bit of clean up at times. Don't break the engine in with a 10" prop, let it wind a bit with a 9x6 or 9x5 breaking back and forth from a wet two stroke to a 4. The large black knob needle valve happens to be one that I prefer from Fox. I've had very good success using these as these were also later offered on the .40's and Mk coffin back series.

         Many times, these engine have a bit of roughness in the crankshaft area. I prefer to dismantle them and chamfer the bushing where the crankface rides up against and do a complete polish of the shaft. While I wouldn't recommend this for a beginner or someone who has no knowledge doing so, remove the plug and slowly turn the engine over checking for binds. The piston on the downward stroke should fall on it's own weight. Many times Fox left burrs in and around the exhaust cutouts which takes lots and lots of running to wear in. I generally do a lap in this area to insure a cleanup of any rough spots to prevent premature wear and to discourage heat buildup.

      What I find a bit odd here is the Higley aluminum nose weight spinner and tail weight on the boom. A bit strange or someone lost the stock nut. I personally wouldn't use that Higley spinner AT ALL on this engine. Fox engineering was quite similar to those on the Flintstones at Spacely Sprockets. The shaft utilizes the same cog setup as the Fox .35 Stunt. Therefore, one can change if needed or borrow the drive washer even though they're not identically the same. Fox didn't provide much of a radius where the shaft meets the drive cogs. The drive washer is completely flat on the back and it seats directly on the square edge where I just mentioned. What can happen is that vibrations from many variables can allow this square seat to snap off where the threaded portion meets the cogs. One remedy is to place a slight radius on the back of the drive washer to allow a complete seat onto the cogs and relieve the pressure on the shaft.