Fox .40

[Michael Massey]

I have 2 new Fox .40's.  One is the ABC and one is just a ball bearing.  Each have about 25 engine runs.  Since I had a damaged needle valve on the BB I will leave that alone.  On the other hand, the ABC has had no issues other than it will not run anything but lean and fast.  You can not slow it down and it quits when you try to run it even a little rich.

I have tried the recommended fuel and fuel of different (lower) nitro percentages.  (It calls for 15% and 20% Castro.)  I have tried different props etc.  Simply, it runs flat out or not at all.  Any suggestions?  I e-mailed Fox and as of yet, have had no response.

Tx.

Mike

[Robin_Holden]

Mike , hi from a British ex-pat in Southern France.

I bought a Fox 40 from Lone Star years ago when I came back to C/L after a long absence. Mine was just the same. Ran it in with great care. Like yours it just wouldn't 'calm down' , just wanted to go flat out.

Like you , tried different fuels , more lube , bigger /smaller props etc to no avail.

Mine was the ' poverty' model as we English say .... the plain bearing version.

Too heavy as well . It's now in its box , well oiled !

I look forward to hearing from some chaps 'in the know' who may solve our joint problem.

Regards from the Charente ,

Robin.

[Balsa Butcher]

Yup, that's the way they run out of the box. 

[john e. holliday]

That is why they are sent to "The Silver Fox" Lew Woolard who is laid up right now.  Haven't heard any bad news so I guess the doctors did his heart some good.  DOC Holliday

[Frank Sheridan]

Without going into any details and revealing any of his "secrets", does anybody know what Lew Woolard does to these Foxes to tame them down? I have a 45 that I haven't used for the same reasons.

[W.D. Roland]

Just some ideas that may or maynot help.

I have had the problem show up in engines that did not have it before and some that were new.
R/C and C/l
Several times turned out to be Fuel--fresh at that.
I would have to look at the can to tell you what brand.
Have to say that one time it was due to wrong type castor oil added to fuel

Other causes have been pin holes in fuel line even inside the tank.
Changing glow plugs sometimes helped.
Lowering compression through head gasket or short plugs.
Run idle bar plugs.
Angle of holes in spray bar to venturi angle.
Crank case leaks.
Leaks aroun threads of needle valve--curable with short piece of silicone fuel line made into a seal.

Now that  said all that  I should say that none of my engines were manufactured after about 1975 except for a few R/C and then none after about 1980.

Let us know what it turns out to be.

David
AMA 51336

[BillLee]

...2 new Fox .40's.  One is the ABC and one is just a ball bearing. ...

Uh,.... SInce "ABC" is a reference to the piston and liner construction, and "ball bearing" is usually in the context of how the crankshaft is supported, did you mean to say "One is  plain bearing and one is just a ball bearing"?

Regards,

Bill Lee

[dennis lipsett]

I built a 38 special a few years ago and decided to put my old 1980 40 R/C converted to C/L engine on it. This was one of the first that Duke made and still carried a lot of the combat 36 lineage in it.
The brunt of the tale is that I have this really neat 90 mph 38 special that pulls like a horse and gives my reflexes the tune up that they always crave.
I occassionally let a few close friends fly it and can tell in an instant who has the 'right stuff' You have to get a rush as you do an outside square at speed, it just dosn't get any better except for the 4 leaf clover. oh  heck it's all good.
dennis

[W.D. Roland]

Ahhh
Not having the engine in hand can only make a guess.
If that's the 6 bolt back plate engine my best guess is you need to lower the sleeve until you have exhaust duration to something about like that of a fox stunt.
Then the head will need raising to drop the compression.
Make sure the sleeve does nor contact crank or other.

I bet if you check the current exhaust duration its around 150+ degrees.

David
AMA 51336

[Michael Massey]

The ABC is truly the construction of the engine and it does indeed have a ball bearing on the front shaft.  The BB I referred to is a ball bearing on the front shaft but probably an "iron" piston/sleeve.  They have a third new Fox 40, that I do not have, and probably at this point a fortunate situation, and that is a plain bushing for the front bearing but is otherwise similar to the BB.  The ABC/BB engine that runs nothing but "scream" is the one I have the most experience with, and at this point, frustration. 

The new needle valve on the new Fox looks good but you have not latitude to change the spraybar orientation.  The other issue is that the "friction" mechanism to maintain the needle valve setting is an "O" ring that, unlike a "click", mechanism, can "spring bacK" from your setting.  I do not have enough experience with the new needle valve to talk about sufficient or insufficient taper on the needle itself.  If I could get the ... thing to break in and adust to anything beyond "scream" then I could comment on the taper itself. 

Thanks for your help and feed back.

Mike