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Engine basics => Engine set up tips => Topic started by: Bootlegger on January 31, 2016, 12:54:07 PM
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Gotta late 50's, early 60's Fox 29 stunt trying to get it broken using 22-26% castor with about 3% synthetic oil and no nitro, after about 1.50 to about 1.75 it still doesn't want to rev more than about 7.5 to 8 grand with from 8.5 x6 to 10x5 props.
I want to build a Lew Andrews Trixter Barnstormer for O T S but I would have thought this engine would turn better than it is, any body got any suggestions as to what to look for?
I am running a Sig idle bar plug in it right now, and am somewhat confused as to what to do next, any help/suggestions will be appreciated...
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They need 10 nitro to run decent. It should turn 8,500-9,000 with a 10/5 if broken in.
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Even better w/15% nitro.
Doug
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Gotta late 50's, early 60's Fox 29 stunt trying to get it broken using 22-26% castor with about 3% synthetic oil and no nitro, after about 1.50 to about 1.75 it still doesn't want to rev more than about 7.5 to 8 grand with from 8.5 x6 to 10x5 props.
I want to build a Lew Andrews Trixter Barnstormer for O T S but I would have thought this engine would turn better than it is, any body got any suggestions as to what to look for?
I am running a Sig idle bar plug in it right now, and am somewhat confused as to what to do next, any help/suggestions will be appreciated...
You might want to check to see if the liner is in correctly. I have a Veco 29 that acted like that and sure enough the liner was backwards. Turned it around and WOW what a difference!
Good luck, Jerry
PS: the exhaust is the high one.
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"trying to get it broken using 22-26% castor with about 3% synthetic oil and no nitro, after about 1.50 to about 1.75...<snip>
1.50 to 1.75....gallons, or quarts? Fuel economy should be pretty good on zero nitro, so I'd think that many gallons would be pretty good. I would prefer the .29 Stunt (thicker liner, smaller and lighter piston), and it will be plenty for a decently light Barnstormer. Might use a 9-5 or 9-6, tho. I'm not sure if the .29 Stunt has the same venturi size as a .35 Stunt, but if it does...it's huge for a .29. Check it and see, 'cause it would tell me to put in a .157" spraybar.
As for the rpm...take a look in the exhaust stack and make sure the cylinder isn't rotated a bit out of synch. It won't run much at all with the liner backwards as previously posted, certainly not 7.5k. You might look at how many head gaskets are in there, or if the glowplug is a short reach...they'll barely run with a short plug. y1 Steve
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My oop's, that is the amount of run time 1.5 to .75 hrs of run time, I had a brain fade and skipped that part..
Need a better "preef rooder" !! #^
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It's funny you bring this up bubba. I just got a NIB late 50's fox 35 so I'll be in this same boat your in!
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I gotta say at 1.5-1.75 hrs its already 99% broken in and look somewhere else for the low rpms. I did't make tach notes on the 29 and I don't own one now, but my opinion is it should run around 10.5k with a 9/6 and +-10k with a 10/6 MAS nylon...a couple hundred less than the 35.
Here's my old notes from 3 Fox 35s to compare a 29 against. From high time to newly broken they gave the identical results and were bench tested at the same time...on 5/29 (Fox Superfuel) all castor and Fox long plugs.
Fox 35
10.5k - 10/6 MAS nylon
10.0k - 9/7 TF Power Point wood
11.0k - 9/6 RevUp Pro 4 wood
10.9k - 9/6 TF SuperM wood
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Hi Bill:
I think that I remember that the Fox .29 was about 500 rpm slower than the Fox .35 according to a test made in M.A.N. in June 1953. This may give you some idea as to what rpm you may expect from the .29.
If you wish to swap a .29 for a .35, let me know.
Good luck,
Frank McCune
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Hi, Guys.
I picked up a brand new/old model Fox 29 at my local hobby shop around twenty years ago.
A 1955 model as I recall.
I broke it in on Powermaster 10/22 50-50 castor synthetic.
The only mod I made was to install a K&B needle valve assembly.
Installed in a Barnstormer, and with a 10-6 Top Flite wooden prop I flew it in Old Time Stunt for around five years and also loaned it to quite a few people to compete with.
All told, well over 700 flights, always with the same fuel.
The Barnstormer is long gone but I still have the Fox and it runs as well as when it was new, with excellent compression and a tight front bushing.
Never ran it 2-4 style - always screaming lean.
Early in the plane's history, I did try a muffler, a well opened tongue type, and the engine overheated.
After that, it was always run with open exhaust.
Never tached it so I cannot comment on engine speed.
FWIW, Bob Z.
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Mornin Guy, I mixed up some 10N 25C 5Syn and the rest methanol and that beast came to LIFE, 8500 R P M and now I have to get building a Barnstormer for Ole Time stunt..
Got another question, what kind of muffler can I use? The engine doesn't have muffler ears, so I need strap on muffler, any help will be appreciated...
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Hi, Gil.
30% oil?
Sounds like a bit much.
Mine turned a 10-6 Top Flite wood at 9,800 RPM.
Read my comment on mufflers.
The exact same thing happened to one of the other guys with a Fox 29 - overheated with a muffler.
Bob Z.
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I fly Fox 35s with and without muff ears, stock and with Hemis. Run 5-10% nitro with 25-29% castor at sea level. No problem with Big Art tongue muffs. Brodak sells the Big Art design. It might be different with the 29 but worth a try.