I had an "oops" on Monday evening.  A Fox 35 mounted on an ARF Flite Streak leaned out and then stopped before running out the tank.  We started it again and opened the Needle Valve - it wouldn't slow down.  I threw a rag in the propeller once, then twice.  I said "I'll bet the motor is loose".  It was.  We tightened it along with the NVA which also a bit loose.   The casing of the motor, especially the head turned sort of bronze.  It's a 50th anniversary edition motor.

Question 1, how can I clean the motor? 

Question 2   Does that mean the motor is blown.

We did get a half decent flight out of it but haven't got the needle set right yet.  It was too rich, if I remember.

When will I ever learn that if you can't seem to change the speed of the engine, then it must be loose?
I'm going to have to start using LocTite on my mounting bolts.

I'm guessing that the bronze color is from cooking the castor oil on the outside of the engine.  You can claim you did it on purpose for the aesthetics, you can use whatever the current cool engine cleaner is, or you can chuck it in a crockpot with antifreeze overnight and scrub it off.

If only the Fox 35 owners would part with about $17,00 and junk that sorry needle valve that Fox sells your engine runs could improve about 100%. No, Don't buy the new NVA that Fox sells they got that one wrong too.. Get a Randy Smith NVA and find out that your 60 year old clunker can really hold a setting for the whole run. or you really can turn the valve more then one click, or it doesn't wobble so much when the engine is running that you can bearly see the valve to adjust it, or your rubber tubing on the needle valve split and the thing is sucking air and not fuel. You get the picture. It's time to get out of the 50's and modernize. period.
Dennis

Thanks for the ideas and encouragement.  I am aware of the Flite Streak ARF front end problem.  I intend to build a new fuselage over the winter, probably elongating it a bit.  I already have the wood. I also have a new Smith NVA on the way.   I have 43 flights on the Streak and I have heard that the front end usually lasts around 50 flights.  I hope it gives me a few more than that.  I have actually increased my sport flying ability to be very confident with horizontal eights and I did my first vertical 8's, very rough looking, before these engine problems.  I'm hoping to ride this baby a little further.   I have an untried Magician and a Smoothie with a Brodak 40 for my next rides.  The Smoothie was just finished or "refinished" and the Magician has one flight with a Fox 35.  I'm hoping to put the bypass insert into it soon. 

I'll give a report once I get some flights in.  Last week was dismal with the crash of a Nobler and this problem with the Flite Streak.  Before that, it was a great summer and I believe it will continue to be.  javascript:void(0);javascript:void(0);

 

Good News! The tightening was what this engine needed.  The almost black headed Fox ran the best it ever has on Friday evening. I'm thankful.  Still the best running plane and motor combination I have, for now.  I'm hoping to take a Smoothie with a B-40 and a Magician with a Fox 35 to a higher plane than this one, at least for stunt.  My problem is time - a 15 year old, a 10 year old, and a church to pastor.  The fuselage will wait.  By the way, the tank on this is an inboard mounted 3 oz. Hays tank and I'm running it on muffler pressure.  It 4-2's really well.

However, I might have the tank just a bit high.  It slows down in inverted and stopped on the third outside loop.  Is it correct that I need to lower the tank a tad?   

No one seems to have said it yet so I'll mention it -

you can run a screaming fox 35 if you want -


 AS LONG AS YOU HAVE ENOUGH CASTOR IN THE FUEL

most important aspect of all the above is to have at least 20% castor in the lube for the fuel.


without it, your engine will become junk in a short amount of time at those high runaway RPM's

  

 

However, I might have the tank just a bit high.  It slows down in inverted and stopped on the third outside loop.  Is it correct that I need to lower the tank a tad?   

Hi Allen,

If it is dying lean, you need to lower it.  If it is dying rich, you need to raise it.  All of this perspective is with the plane on its LG.

The PA NVA will make it much nicer to set the needle.  Just don't tighten the needle's "locking nut" much more than finger tight.  It doesn't need to be tightened to the point that you cannot move the needle. 

Big Bear

Your theory goes against all conventional wisdom and the expertise of people like GMA and many others.  28% all castor is the accepted norm.  You may have an exceptional engine?

Floyd

If it is dying lean, you need to lower it.  If it is dying rich, you need to raise it.  All of this perspective is with the plane on its LG.

By the way, what is LG?

It is dying or running slower from running rich in inverted flight.

The reason I thought that I might to lower it is because I would raise it while it while sitting upright,  which, I thought would lean it out in inverted since the outflow of the fuel would would be closer the plane on which the fuel comes out of the hole in the spray bar.  However, that would allow more fuel to come in and make it run richer! Is that correct? However, as I think about it, I think your right.    I didn't install the new NVA yet but will do so soon.

Thanks for the tip about installing it.  My brother installed his first on a Fox 35 and it has run well but he had to tighten and tighten and tighten.

It was great to be able to get good glow plugs from Randy - Thunderbolt and Glo- Devil. I was wondering where to get them and was delighted to get them from him.  We installed one in one of brother's Fox 35's and it ran better immediately.  Wow! Learning so much.   Thanks guys!

Bob,
   Knowing who you are, and your abilities, I concur. You can run a fox 35 on 10% castor and 10% synthetic.

but, if you were a newbie, I would still tell you to run 25 to 28% castor for any of the older engines til you develop some engine expertise.

Better to be safe than sorry.

I've run foxes on no Castor - but I don't run them hard and it was only for a season when all I could get was the local RC fuel.

They still run fine but I wouldn't want to have one scream on that fuel -

   

Is it time to review the wig-wag tank height check?

Because centrifugal force - CF -acts straight out, gravity straight down and maneuvering g loads at right angles to the wingspan direction, we can pre-set tank height so that the engine run doesn't change upright and inverted. We can simulate the direction of loads on the fuel, but not the actual load values, unless we are flying alongside the model...

The angle of "gravity direction" the fuel feels in flight results from CF, gravity and maneuvering forces. In level flight, CF is about 3g as a rough rule of thumb. So, in level flight, the fuel acts as if the force on it is at the direction of the diagonal of a rectangle with the top edge 3 units long and the vertical side edge 1 unit high. In upright flight, the diagonal points out and "down" (towards the wheels. In inverted flight the diagonal still points the same direction, but since the model is upside down it now points out and "up" (towards the 'cockpit.')
(This covers maneuver loads, too, since lift IS at right angles to the wingspan when the model is level, inverted or upright.)

How?

Start the engine. Set it a bit rich so you can hear it go leaner if the tank is too low, or richer if it is too high.

Hold the model with the fuselage centerline level, and roll the wings so the outboard panel is straight down. This is just a convenient mid-point between the rolled positions you'll use next. Note the sound, or tach the RPM, in this position.

Keeping the uselage centerline level, roll the wings to about 45°, say "cockpit up." Note any RPM or run change.

With the fuselage centerline still level, roll the wings to the other 45° position ( say "cockpit down"). Note RPM or run change.

Think about this. It goes leaner in the roll position where the tank is too low, and the engine has to draw fuel "uphill." To prove that, notice that it goes richer in the other rolled position where the fuel is being "poured downhill" to the NVA.

Repeat the roll position tests until you are sure which way the tank is 'off' from where it should be. A quick, safe way to stop the engine is to point it nose down, outboard wing up.

Shift the tank to reduce the RPM (or run) difference between the rolled positions. Run the wig-wag test again.

Two or three times through this procedure should settle the tank where there is NO RPM/sound change at the ~45° rolled positions. The model should now be safe for first flights without flameout or floodout. ...Should be very close to the final position where upright and inverted, and inside and outside runs are identical. But, like everything else about model airplanes, there may be some final tweaking to nail it.