Fox 35 Stunt

Stuka Stunt Main Forum · 8 of 8 known posts recovered

Mike · Sep 22, 2001 09:34 PM

Just purchased a Fox 35 stunt motor which has never been run for
35.00 but there were no instructions or paperwork in the box. Can
anyone help suggest the proper starting needle setting or specific information on breaking in the engine?

mop

The Kiwi · Sep 22, 2001 11:19 PM

#1 source

LAST EDITED ON Sep-23-01 AT 10:08 AM (CDT)

>Can anyone help suggest the proper starting needle setting
>or specific information on breaking in the engine?
>
First off, the needle valve assemblies apparently differ so very much from one to another in some manner that a specific number of turns is nearly impossible to be certain about.

Second, Peter Hess asked the same question here once. I have broken in several of them myself, though it's supposed to be easier now. Point your mouse cursor onto the next line and click on it to see what I told him (and stuff other folks said as well):

(http://www.clstunt.com/htdocs/dcforum/DCForumID1/327.html#1)

I've never had good luck with either 11" props on Fox 35's or with various extra wide-blade props on this type engine:

(http://www.clstunt.com/htdocs/dcforum/DCForumID1/327.html#4)

Kiwi

Ty M> · Sep 23, 2001 12:35 AM

#2 source

I mount mine on an EZ Just test stand (old as dirt but still works) install a 9inch 4 inch pitch, 5% nitro fuel, at least 28% castor oil fuel (Sig makes some and I guess Fox still does too) I open my needle valve at least five turns, prime in the venturi, choke and pull the prop through four or five turns, hook up the glow plug, and flip, flip, flip until it starts. When it starts, immediately turn the needle valve to as rich as it will run and let it slobber there for about one minute. Pinch the fuel line to kill it and walk away. Let it cool. Let it cool. Before mounting it, make sure all screws are tight, plug is tight. Once the engine has cooled to the touch, repeat the starting procedure, but let it run for two minutes. I repeat this up to a five minute run, then I start turning the needle in a few turns until I just have a four stroke. As it gets warm, you can hear it go 2 stroke for a second and then back to a four stroke. Do not rush the break in of these engines. It will last a long time on 5% to 10% nitro and pure castor for lube, no synthetics. After about 30 to 40 minutes run time, install a 10 inch 4 inch pitch prop. Use wood props. Let it run for another 10 to 15 minutes like the last 10 minutes on the small prop. Mount on a plane and fly 10- flights of level flight, some climbs and dives and no stunts. After this flying break in, go for it. Keep it clean and oiled. Have fun. I still have Fox .35s from the 60's still going strong.

Steve Fitton · Sep 24, 2001 07:32 AM

#3 source

Mike,

The most important thing you can do for your Fox 35 is use the right fuel. Fox superfuel or equivalent (5% nitro 29% all castor lube) or in a pinch the sig 25% all castor fuel. I've broken in foxes both by the teststand method and by careful flying. The only way to quickly kill one is use the wrong fuel-I've done that, too.
It seems to me that the Fox website has a printout of the FOX 35 instruction sheet. I don't have the url, but I bet a search for Fox manufacturing will turn it up. You can read exactly what would come in the box with your motor from the website and see what they recommend for breakin.

Steve

Steve Fitton

PeterH · Sep 24, 2001 07:58 AM

#4 source

It may not be appropriate to take this engine and attempt to run it, even though the crankshaft is free to rotate. Fox engines are run by the manufacturer before they're packaged and shipped, and the lubricants in the fuels are castor oil. This is a fine cement for gluing together engines after not-too-long a while. I have very often found the wristpin locked to either the piston or the connecting rod in engines like this. I am inferring that this engine is not particularly new, just unused. If so, it may well be a candidate for stripping, cleaning, and reassembling. A wristpin that is stuck to either the connecting rod or the piston will be a party to premature wear involving those parts. In order to come apart, I think a Fox .35 connecting rod needs to slide as far to the rear of the piston as the piston allows, after removing the cylinder liner - - ain't much room in there. I realize my comments might be hyper-conservative, but that's what my limited experience has offered me.

Peter Havriluk

Currell · Sep 24, 2001 12:11 PM

#5 source

It's true that wrist pins can get stuck, but the odds are in your favor that this did not happen. This is based on experience with many, many Fox Stunts. Having said that, I would load the engine with some penetrating oil and let it sit for a day or so before running it. If the wrist pin is stuck, this improves your chances of loosening it. I don't like to disassemble an engine unless it is necessary.

I have a different philosophy on prop selection when breaking in an engine. I like the flywheel action of a larger diameter prop, since it aids starting. You may, then, opt to use a 10-3.5.

Currell

The Kiwi · Sep 24, 2001 03:33 PM

#6 source

>I have a different philosophy on prop selection when breaking in
>an engine. I like the flywheel action of a larger diameter prop,
>since it aids starting. You may, then, opt to use a 10-3.5.
>
Having tried a wide variety of break-in props, I kept going back to what I found worked best all the way back to the very dawn of my experience (and it's probably still the same old prop). I'd been quite unsuccessful with a series of 49, 51, & 60 sized old Sparkies that I'd acquired for prices like 75 cents or a dollar each from older kids wanting money for new glow engines.

There's a dumb story to go with that period of frustration, but right now it's enough to just point out that I ended up with some left over 12 and 13" diameter wooden props. I cut a 12-4 or 12-5 down to 9" at first, and that gave me plenty of flywheel, but there seemed to still be a bit more load than I wanted involved, so I cut some more off. It's about 8 to 8 1/2" diameter, and has been run on somewhere between 50 and 60 engines, I think.

Try trimming some tip off a big prop like that and see how it works. You may like it better than a full size "regular" prop.

Kiwi

Bigiron13 · Sep 24, 2001 09:39 PM

#7 source

I agree with Kiwi. Take a 11 or 12 inch prop with 5 or 6 inck pitch and trim it down to 8 1/2 inches . be sure both blades are the same length and that the prop is ballanced after all trimming and sanding is done. I use a Master Airscrew.
Lots of flywheel action and not too much load on the engine.
Bigiron

Bigiron13