1949 Fox .35 vs. Newer Fox .35 Stunt in Shoestring???

[frank mccune]

       Hello All:

       How well would a 1949 Fox .35 Stunt fly a Goldberg Shoestring.  The engine is in great nick and appears to be unrun.  Will this engine provide some old time performance without the burp?  For some reason, I would like to hear this engine power a plane after lying dormant for many decades.

      If this does not work out well, then it is time to mount a Brodak .25  and join the Now Generation.

      Thoughts/suggestions?

                                                                                                                      Be well,

                                                                                                                      Frank McCune

P.s.  Hey Brett, don't let this post get to you as I think I know how you think about me struggling with obsolete engines.  I still have my O&R .60 to mount in a Humongus. Lol  I mothballed my 1948 McCoy Sportsman .19 and .29 engines due to their lack of power but maybe someday...
 
   

[john e. holliday]

I guess I'm one of the few that still flies the older Fox .35 and have not notice a burp when used on profiles.  But then again I'm hard of hearing.

By the way I use uni-flo tanks.

[Gary Dowler]

2-1/2 years ago when I first got back to flying, the first thing I built was a Shoestring Stunter.  I powered it with a Fox 35 stunt that was left over from decades past.  It flew fine.  As long as I gave it fuel with 30% oil (10/20 syn/castor) that is.  It simply would over heat on 20% (50/50 syn/Castor) and wouldn't run out a tank.

Then Brett educated me on the 20FP.  Swapped it and, after resolving a NV issue, it flew even better.  But I really had no issues on this one at all with the Fox.

Gary

[Dennis Toth]

Frank,
The 1949 Fox 35 is the same as the 1960, 70, 80, 90 etc. The only difference is the case on the 49 is sand cast and a little thicker than the rest. There were some minor changes to how wide Duke had the ports cut but nothing that made any difference in power. My advise is the same with whatever Fox 35 you put in the plane. Use a Randy Fox NVA or a turned down ST to match the original Fox NVA. If a side mount, put the stick in the bypass (the 49 case may not need this). Make sure the engine doesn't have any bind spots as you as you pull through the full stroke with all the head bolts tight (the sand cast case is a little better resisting twists as you tighten the bolts down). If you change the head bolts to socket heads make sure you file them down to 0.168" OD (this is the diameter of the Fox bolts) to prevent binding against the head boss.Use 1/32" crush pads under the mounts if you use aluminum pads under the engine. If open face exhaust run 5 - 10% N, 27-29% oil (50/50 syn/castor is ok) on a 10x6 RMS prop, if running a muffler drop to a 9x6 BYO prop (this reduces load and prevents overheating and run-a-way with the muffler). Use a "hot" plug like an Enya No.3. Use a uniflow tank with the vent plumbed to be on the inside off side of the fuse pointing into the airflow. Don't try to fly to rich, the Fox does well just breaking lean with the nose pointed up at about 45 degrees as a starting point, adjust needle from there.

Go fly, it will be fun again.

Best,   DennisT