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General control line discussion => Open Forum => Topic started by: Steve Maines on November 16, 2023, 08:07:38 AM
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I have a Fox 35 that I believe is circa 1952 that has seen some use. Still has excellent 'pop' when flicking over the prop, but the exhaust has some damage that looks to have been maybe from over tightening a strap-on exhaust, but also seems to be a file mark for some reason. I know these are often run open stack without any muffler, but will this damage affect performance? I'm thinking not as it's a cosmetic issue, but thought I'd ask.
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Steve it does look like the damage was some effort to adapt a muffler and was then torn off in a crash. As long as the case wasn't contorted in some way it should run OK. I run my Foxs open face and they run better without the back pressure and retained heat of a muffler. I'd say just mount it up on a test stand and give it a go. A caution though- without a doubt this was run on all-castor oil fuel. I would NOT put fuel with any synthetic oil in it and be sure you are using 28-29% castor oil in your fuel. Synthetic will peel away the castor 'shellac' built up in the motor which is actually creating the good piston seal and render the engine as junk. You may still be able to get some useful life from the old motor if you treat it properly. Duke Fox used to say these engine were built to last 100 hours. It takes a LONG time to accumulate 100 running hours. This assumes though that you use the correct fuel and you don't run the engine too lean and overheat it or overload it with props too big or pull too large or heavy airplanes with it. I've seen a few that were nearly black that still ran pretty good. I've had more go bad from sitting on the shelf and corroding away inside than anything else. And there is another caution- if on the test stand it throws a heavy stream of dark crud- black or dark gray- it is puking corrosion. The engine is basically toast. I've seen one or two that started to run nice on the stand then within a few minutes start shaking violently as it destroys itself. If you get a couple good tankfuls through it and it's still smooth you should be good to go.
Dave
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Hi, Steve - here's what a 1952 Fox 35 looks like.
Bob Z.
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Hi, Steve - here's what a 1952 Fox 35 looks like.
Bob Z.
I'm thinking mine is the same........no? The needle valve has had a previous owner solder on a piece of brass tube that I have since removed.
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I'm thinking mine is the same........no? The needle valve has had a previous owner solder on a piece of brass tube that I have since removed.
Yours is a '59 according to Andersons blue book of engines as far as i can tell......but so what? It'll run just fine if the compression is good and the crank isn't bent!
Good luck, Jerry
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From when the engine was first introduced on , what 1947 until they went to the more modern casting techniques over time, the engine really never changed. It may have gotten a bit heavier as they cast in more aluminum, and then added muffler ears and such. The flaws in the exhaust could probably be filled in with JB-Weld just for looks. I have welded broken exhausts with by TIG welding them with good success, but since there is no stress on the joint the JB-Weld may work OK. You could maybe even add on a longer exhaust stack that way also but forming it from sheel aluminum and making fit as tight as you can before applying the JB-Weld.
Type at you later,
Dan McEntee
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OK, so whatever vintage it might be is irrelevant and I'll just do some bench runs to determine if it's a runner or not. The exhaust damage is cosmetic so will ignore that. My challenge is finding glow fuel with only castor oil and at the percentage these oldies need. I might have to ask around to see if guys mix their own and what they use. I'm in Canada so getting the ingredients might be a challenge.
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If you don't mix it yourself you can order whatever you want from FHS Red Max fuels. I don't know about shipping cross-border but I'm sure they can answer that for you.
Dave