Fuel for Fox 35

Hi guys

I would like to minimise the gum buildup on my new Fox 35 so is it OK to use some synthetic oil in the mix? If so, how much? And how much nitro in such a brew?

I use Cool Power synthetic and locally packaged model fuel castor for my ABC/ABN Scheurle engines. Can I use a little bit of that in the Fox

Cheers

Repeat after me!

29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!
29% all Castor for Foxes!

Got it?

On the other hand, Bob Zambelli and I use POWERMASTER GMA 10/22 with zero problems.

See Ya

Bigs: Disagree. For Foxes, I have been using 25% oil with a mix of syn and castor (majority castor) for years, with no problems.

And they don't gum up.

Essentially what I'm using for the ABC's.....50/50 mix of Powermaster 10/22 Blend and Powermaster 5/29 All Castor. Gives me just over 25% Oil....mostly Castor and 7-1/2% Nitro. Same blend works great on a standard engine - well broken in on straight 5/29...which is always a safe bet.

AFAIK, Larry Foster (L&J) recomends high nitro (at least 10%) and high oil, most if not all castor if you plan on running them a lot.
The Fox 35 is a thin casting, and heats up easily. The high oil and nitro helps to cool them. He has spent a LOT of time working and testing the Fox 35. Maybe BigIron will have something to say, too.
I don't take chances, those old iron piston/steel sleeve engines just like oil! I will use 10% Sig 25% all castor when I can't get 29% oil. A little Klotz added to the Sig doesn't seem to hurt, plus the mandatory dose of Aero Products Snake Oil.
Bill <><

One big question - is your Fox new or is it one with a lot of running time on it? If it is new, a little synthetic oil is OK. If it is older, the synthetic will clean the piston/cylinder varnish and you may find that you now have a worn out engine.

For new Foxes, Excaliber (fuel guys in Phoenix) have a really great Fox blend - 15% nitro, 25% castor, and 3% synthetic.

Steve
The older I get, the better I used to fly!

For my stunt flying operations I take Fox Super Fuel (5%nitro 29% castor oil) and mix it 50/50 with Dukes fuel (10%nitro, 20% castor oil) and then add one ounce of Klotz synthetic per quart (4 oz per Gal) to keep the engine clean. The end result is 7 1/2 % nitro and 28 % oil. I have added more nitro on occasion to see if there was a noticable improvement and found that there is some improvement. I recommend for good power and long engine life 5 to 10 percent nitro, and 25 to 29 percent oil, most of which is castor oil with one ounce of synthetic per quart of fuel added. The engines that I have been running that mix in have been lasting five to ten years. (one in my All American Sr went 12 years before I gave the plane away (without the engine). The engine still has good compression, but the shaft is very loose in the case.
the most important thing for the Fox 35 stunt engine is to get a GOOD breakin and try to never get a too lean run. A stuffer backplate will aid in the longivity of the engine also.

Bigiron

>A stuffer backplate will aid in the longivity of the engine
>also.
>
> Bigiron

Marvin,
Please forgive my ignorance on this, but just what does the stuffer do for longevity? Not *questioning*, just didn't know that was also a benefit. Does it significantly help in crankshaft play, etc.,?
Thanks!
Bill <><

LAST EDITED ON Oct-06-04 AT 10:39 PM (CDT)
 
Bill, I am a little reluctant to answer that question as I already have (several times) on this board and others. It ALWAYS seems to draw out a bunch of naysayers and snide remarks such as the BOM threads do. But for the sake of those who are new to the subject, here goes.
Back in the early 70s when Foxberg and Foxy Hazel (and other sport racing events) was just starting, most of them required STOCK engines. Many still do. Most of us who were interested in the events started working very hard to get our act together so to speak. While in actual contest racing events, we would only run about 150 to 200 miles a year, most of us would run that much in a month during practicing. (Sometimes that much in a week). The fuel of choice and REQUIRED by most contests was 10% nitro and 20% all castor oil. That small amount of oil along with the LEAN needle settings for racing. Began to tell on the old Fox engines. I (and others) was going through THREE crank shafts and TWO piston/cylinder assemblies a year. The shaft crankpin (where the rod fits onto the shaft) was wearing in a taper as much as 0.015 inch TAPER from the back of the pin to the front of the pin. (a distance of appx 0.25 inch) Upon looking at that and the face of the backplate it became obvious that the rod was sliding forward and aft, hitting the backplate, with each revolution. I removed the piston/cylinder and rod assembly and left the shaft installed in the case with the prop on and tight . I reinstalled the backplate WITHOUT a gasket and measured the clearance between the face of the backplate and rear end of the crank pin with the shaft shoved as far rearward as the thrust washer would let it go. The distance ranged from 0.040" to as much as 0.070 inch. Over 30 engines were checked for that range. So I decided to come up with the stuffer plate that Fox mfg now produces. While the stuffer backplate was definitely not a new idea, the coating that I (and now Fox mfg) put on the face of the backplate WAS new. It is a coating that has very low friction when rubbing against aluminum (the rod) and yet will not peel nor chip off. The stuffer backplate goes deeper into the case and clears the crank pin by 0.005" or more. I nor Fox mfg ever claimed that the stuffer was to give more RPM or power. It was solely designed to reduce the wear on the crank pin. Now as I stated earlier, most of the sport races required STOCK engines so the stuffer was and is still NOT legal for the races, BUT the majority of running in race conditions was in practice, we could use them there. Since I have been using the stuffer backplates, I have yet to wear out a shaft and the piston/cylinder assemblies have been lasting up to near two years .
As an added note, with the stuffer in place, the vibration of the old Foxes was reduced notably on most engines and on some, the tendency to burp when transitioning from inside turns to outside turns was reduced or eliminated. While it was not designed nor intended to do those last two things, I (nor Fox mfg) are going to look a gift horse in the mouth. I will happily accept any benefit that may happen along.
I know that the racing and stunt run conditions are vastly different, but the rod play and wear is still there and can be alleviated by the use of the stuffer backplate.
Some who read this board claim up to 300 rpm increases, but I have not noticed that in an overall spectrum.

Hope this has answered your question. If not, I hope it at least puts you to sleep with boredum.

Bigiron

Bigiron,
Thanks!
As I wrote the question, I was considering the crankshaft play, but wasn't sure that it would be of that magnitude. Makes perfect sense to me!
I had only heard about the "performance gains", I'm glad you explained it.
Thanks again,
Bill <><

You will ruin your fox engines with anything but castor based fuel! They will run good for about 2 flights and then the engine will start to tighten up and overheat on around the 3rd tank full and it will brown the head of your engine from the over heating and after several runs will ruin your engine.

Take it from someone who knows first hand! I bought some fuel at the local hobby shop in my area and asked for a 25% castor based fuel and the guy said he only had 20% but he could add some castor to the fuel. I said to go ahead and didn't bother to double check the label on the fuel bottle. I went flying several times using the fuel and started having all kinds of problems with my Fox .35's and my McCoy .19. To make a long 1 month story short and the cost of wrecking my McCoy. I finally checked the fuel bottle lable after trying tons of things to figure out what the problem was and noticed it was a 50/50 synth castor blend that had an additional 6% of castor added at my request!

It almost wrecked my 2 new fox's and the McCoy it shot

I would sure compare Marvin's FOX experience with anyones...he knows what he is talking about

See Ya

Hemlock: Your results are puzzling. As you can see, many people, including myself, have been using fuel quite similar to the mixture you stated in Fox Stunts with no problems.

I am guessing that because the engines were broke in with a 5% Nitro and 25% Castor fuel the 15% castor was not enough to make the engines run cool even with the 10% synth oil in the mix.

Marvin, since I am still working on those CAD drawings—when I get the chance—there is no chance that you will ever put me to sleep.

To answer, other questions, the Fox is NIB. I have a stuffer backplate and I intend to fit a Randy Smith crank and put a 3/16" wide filler in the transfer port to improve the side-mounted performance.

The mechanical engineer that I was some years ago recognises that the several uses for the oil in a Fox 35. Also, when I was running OS Pets and Max 15 Mk IIIs as my main stable as a kid, I had some of the best running motors at the park—all running 20% or 25% Castrol R.

Given the engine configuration I was hoping that someone might say that I will achieve my objective and not wreck the engine with 25% Castor, 3–4% Cool Power and 5–10% nitro depending on the specific requirements of sunny Sydney.

Thanks for the input guys

LAST EDITED ON Oct-07-04 AT 11:14 AM (CDT)
 
Geoff, you keep mentioning "cool Power" at 4 to 5 percent. Is that an additive or what?? Cool Power over here is a fuel that is NOT good for Fox 35 stunt engines. If it is an oil (synthetic) then it is probably ok to add it to your engine to aid in keeping it clean. If it is a good oil additive, then the fuel mix that you list will be just fine. Just don't get any scorching lean runs.
As for the two small engines you listed as finding the fuel ok, they have a LOT more cooling fin area and being smaller, less loads on the bearing surfaces with a corresponding less need for as much oil.

Bigiron

I've got lapped iron engines, Foxes, Vecos, K&B, McCoys that have never seen ANY synthetic, and they have lasted for years with only a little gumming up. I burned out a good Fox 59 on my first (and only) trial with straight synthetic. Also turned a McCoy Redhead 35 into a Blackhead the same day. These lapped engines seem to run hotter on anything less than about 60/40 castor/synthetic. Since most of the time all we can find locally is about 18% 50/50 blend, I usually add about 6-8 ounces Baker's castor to a new gallon. The local R/Cers who use only straight synthetic on their ABC type engines get the RPMs, don't have a lot of mess to clean, but seem to have to replace bearings at least once a year. I've got severral 1960s needle and ball bearing engines with the original bearings stillin them and shiny with no wear or corrosion.
Castor rules!!!

According to Duke Fox himself, Fox superfuel has 1% synthetic oil. It is used as a detergent. I don't know if it has 28% or 29% castor.

Thanks to everyone

Marvin

The Cool Power is synthetic oil that I assume is used in their fuel mixes. Bri(stunt) distributes it in Oz and uses it himself.

It seems like the question has produced some interesting answers.

Having never heard of, nor used, the cool power you speak of, I cannot speak for sure about its effect on the Fox 35. I would assume though that since it is used by the makers of your fuel, that it is acceptable as a good lubricant. Used as an additive in the range of 2 to 4 percent along with the rest of the lubricant as castor, I see no reason that it would be any different than the Klotz that I use. Just try to keep the nitro in the 10 % or less range and the total lubricant in the 25 to 29 percent range with the majority castor.

Bigiron

There some givens in CL Stunt that one can fight against, but never win.

Fox 35s and lots of castor is one.

When I first started flying CL Stunt I was way too smart to go for that 29% oil crap. And I had pretty good engine runs using 50/50 blends of castor and klotz for lube.

It was not until I bit the bullet, bought paper towels in bulk, liquid cleaner by the 55-gallon drum, and started using all-castor fuel blends that I got that last bit of performance, consistency and long engine life.

SIG 10% w/25% castor is a real good fuel. I used to like spiking it up a little bit with nitro, but didn't always do this.

If you do not have a bullet-proof fuel feed system and/or the local goat-roper sets your needle for you, 29% castor is the ultimate in protection.

My favorite fuel blend for the Fox 35, albeit an L&J Custom, is 20% nitro, 25% castor, 3% Klotz, balance methanol. Mileage went down, Don McClave didn't like the slightly earlier, harder break, but I liked it just fine.

Just thought I'd throw my 2 cents worth in here. I've been running
Fox.35's for many years, and always used fuel with high-percentage
castor oil exclusively.
About three years ago, I became fed up with having to "de-carbon"
the engines every few months. They would actually seize while I
was starting them, due to varnish formation on the cylinder walls.
I'd dismantle the engine, and polish the piston and liner with
Simichrome metal polish to remove the varnish, and the engine would
be good for another few months. (To be fair, I was getting the same
conditions with OS 35S's).
Taking the advice of a fellow club member whose vast experience and
skill I respect, I took two new ("NOS") Fox.35's, mounted them in
Ringmasters, put 9 x 6 Rev-Up props on them along with mufflers and
uniflow tanks on muffler pressure, and began what is now a three-
season-long experiment using *nothing* but GMA Powermaster fuel,
10% nitro, 22% oil, which is 11% castor and 11% synthetic. (50-50).
These motors are the most reliable I've ever owned. They deliver
a level of performance I've never gotten from a Fox.35.
They show no wear. They even smell better!
They are not varnished. They start on the first flip (usually).
Needless to say, I'm *sold* on the Powermaster fuel, and forgive me,
but I'm going to relegate the "castor only" mantra to the same
category occupied by all the horror stories about unleaded gasoline
dating back to the 70's. (With respect to Duke Fox).
I took this up with the manufacturer of the fuel I was using for
years, and he was arrogant and unfriendly, unreceptive to my
inquiry about the oil, and basically told me I was a fool for
using such antiquated engines anyway, and what did I expect, and
he hated to make that fuel that had all castor! I won't identify
him because I really don't want to start anything, but I'll just
say that I have no intention of ever using *any fuel* but Powermaster
from now on! I'm running this blend in Foxes, OS Max's, Enya's
and I'm not having *any* problems with it.
(I have no connection with that company - - usual disclaimer).
Just my opinion - - - I'm not an expert, but I know what has been
working for me!
Regards,
Dennis T.

Dennis,

Powermaster also does a GMA Blend for Fox .35's with either 5% or 10% nitro and 29% all castor oil, with the balance methanol. It is a bit messy to clean, but I have had none of the problems you describe with my Fox .35's while using it.

That said, I have been experimenting for the last three years with a Powermaster fuel of 7.5% nitro, 25.5% lube (of which 80%± is Castor and 20%± is synthetic) with no ill effects that I've noticed, with the one possible exception of a sloppy crankshaft bushing in one of the three Fox .35's I've tested. That, however, may be the result of a thirty year use of that particular engine without a rebuild, rather than the new fuel brew. I, too, have been using this fuel in a Max-S .35, as well.

I make the fuel blend by mixing the Powermaster GMA Fox blend (5%/29%) with an equal portion of the blend you use. The engines do seem to have a bit more power and the planes are just a bit easier to clean after a flying session. I am extremely careful to avoid lean runs, though, and because GMA and Duke Fox did convince me over the years that Superfuel (or its equivalent) was the fuel to use in those Fox .35's to best protect them, I've been very cautious. Those two late gentlemen knew those engines much better than I probably ever will, and it's hard for me to break with them on this.

Thanks for your reply, "Sourdough" - - -
Here's what I think is happening (and I could be *completely* off
the wall here), but I think something has changed the quality of
the castor oil that *some* of the fuel suppliers are using.
This is why I called the manufacturer of the fuel that was ruining
my engines. I wanted to *learn*, and asked about quality variations
in oil, and he got all huffy, and told me that "all the fuel companies
in the country get their oil from the same tank in New Jersey"!
Now whether that's true or not - - - I don't know.
All I know is that I don't remember *ever* having such varnishing
problems before I began to use that persons fuel. Since I made the
switch to Powermaster 50/50, I have not had *any* fuel-related
problems at the field.
And by the way, the last Fox.35 that started to seize IN FLIGHT
I sent to Fox, along with another one that had chunked a wrist-pin
keeper and practically sawed the liner in half.
The one that was varnished and tight, they sent back "as was" and
wrote that there was "nothing wrong with it" and that'll be 35 bucks!
The other one they put a liner and piston in it that looked as if it had been sanded, sent back to me smelling of WD40 and another 35 bucks
due. That's the last time I make *that* mistake! I thought at least
they'd "throw me a bone" with the one that self-destructed.
Anyway, these Foxes are like old Harley-Davidsons - - - every one is
different to some degree, and once you, as the owner, finish the
machining on them and correct all the deficiencies, they run darn
well!
Thanks for your interest.
Dennis T.

Dennis,

While I was never a customer, I do believe you have discovered why there are quite a number of Red-Max customers who are now ex-customers. Why you didn't feel like naming the company is beyond me, as this is (almost) common knowledge amongst CL folk.

In any case, even for people who may be using their fuel quite successfully, representatives of this company have a slightly flawed record when it comes to dispensing accurate information as it relates to oils and various fuels.

And I stand by my loads-of-castor statements as applied to Fox 35s. I strenuously and for several years resisted what "everybody knew" about lube for Fox 35s, mostly by mixing castor and Klotz in 50/50 mixes, from 20% total oil content up to 28% content for my Fox 35s. There simply cannot be any further debate as to what's best. At least not until the next "miracle" lube comes out, we use it for two years, only to discover we never should have strayed from bucket loads of castor.

Dan

Dan and I agree 100% on the LOTS OF CASTOR OIL in the Fox 35 Stunt engines.
Lately (in the past two to three years, I have noticed more and more engine varnishing occuring on engines running mostly castor based fuels. Even some (like some of mine) that have a small amount of Klotz added. I have come to the conclusion that there IS something in the fuel that ain't supposed to be there.

A suggestion---- Take a gallon or quart of the fuel you are running and allow it to sit overnight or longer without being disturbed. Carefully lift it up and look through the fuel toward a light from about a 45 degree angle from the bottom to see what is settled out. Now gently rock the jug around and watch the sediment.
It appears to me to be a fine sand. Under 30X magnification it appears like fine river bottom sand, BUT it so fine that I cannot get it filtered out. It passes right through paint filters, coffee filters, silk panty hose and the bronze RC tank filters. I haven't tried a Chamos skin yet.
I have found the same appearing sediment in Fox brand fuels, Sig brands and Power Master. Those are the only brands that I have checked. Some even had some Klotz added. The addition of Klotz only made it harder to detect as the red color masks the redish color of the sediment.
To stop the GUMMING of my engines I let the fuel settle a couple of days and then siphon off the top down to about an inch above the sediment and use the clear stuff. Out of four cases of fuel(16 gal) I will lose about a pint of bad fuel. Pouring the bad stuff into a common container and letting that settle out, siphon, pour the remaining bad stuff into a Qt container and siphon again. I wind up with about one quart or less of really bad stuff, and a lot of good clean stuff.

Bigiron

Oh, thanks! Why couldn't this sort of information come from a known whack job so I could just blow it off and live in peace?

But, no! It just has to be Marvin, a man not known for screaming wolf. So off I go to check some of my own fuel for refuse from somebody's gold-fish bowl...

Again, thanks a lot...

Dan

--insert butt load of smiley faces, your choice as to emotion being emoted--

Well said Dan,- glad to see you still got it In you.--Paul

Excerpt from FHS Supply, Inc. - Red Max Model Fuels

http://members.aol.com/fhsoil/Castor.html

Interesting comments... I believe this subject has been discussed before.

Quote:

As stated before, we have always recommended our fully synthetic oils for all types of engines. After that, we were content to let the customers decide whether they wanted any castor oil in their fuel. However, changes in the last few years in the way that castor oil is produced have modified our position. In the past, castor oil was manually pressed from castor beans. Nowadays, castor oil is chemically extracted from castor beans. A by-product of this chemical process is a chemical residue that separates in methanol and that glow model engines are quite sensitive to. This will appear as anything from a thin whitish cloud that is difficult to see, to easily visible large (sand size) particles, white to grey. Later, cloudy grey and black formations appear near the bottom. We have found that it doesn't seem to cause any wear problems, but causes many kinds of throttle and idle response problems. Currently produced castor oil, which is exported from places such as India and Brazil, is made in this fashion. All attempts to date by us and by our suppliers to remove these impurities have failed. The problem is aggravated by increased nitro and methanol percentages, and also by cold weather and freezing. The problem is hidden temporarily, but not cured, by heating, mixing, and filtering. It will just fall back out in a few days.

You don't have to believe us, but this is an experiment that you can do yourself. Just take your sample of castor, and mix it about 20% Castor to 80% Methanol or Methanol/Nitro blend (a typical fuel mixture). Depending on the quality, it can go bad in anywhere from a few hours to about two weeks. Put it in a cooler or freezer to speed up the effect.

Dick,

I would just as soon you hadn't brought this up. I believe that what Marvin is seeing is not related to the thoroughly de-bunked "bad castor" story that years ago came out of FHS.

Not a lick of my "AA" castor from SIG has ever lived up to the claims made in the release you have posted.

>Dick,
>
>I would just as soon you hadn't brought this up.

Didn't know you were in charge of "bringing up"!

> I believe
>that what Marvin is seeing is not related to the thoroughly
>de-bunked "bad castor" story that years ago came out of FHS.

So what is your explaination?

>
>Not a lick of my "AA" castor from SIG has ever lived up to
>the claims made in the release you have posted.
>
>Dan

To quote you.... "At any rate, I take Marvin quite seriously on this sort of stuff, I'm not so sure we should just let the thread die a slow death."

Just doing my part.

As I told Dan in our conversation Wed evening, I bought some castor from Sig and Fox, and mixed my own fuel using locally bought methanol and nitromethane from the local race bunch and put in a container that I KNEW was clean and DID NOT get the material that I see in the fuels that I have bought already mixed and put in plastic jugs.

By-the-way Dan the burn down test didn't work too well. The oil still remained and was so thick and turned brown so I could not see what the contaminant was doing. I am going to try to look at it under a microscope next.
Bigiron

My original post has brought up some interesting information!
Dan ("DirtyDan"), the company was *not* Red Max but S&W. You might
not even know this company, as it's out in Pennsylvania, and I
suspect it's a "one-man" operation.
I used his fuel for *years*, and started to get this incredible
varnish build-up when I began to use his "Fox Fuel", which was
(if memory serves) 27% castor and 5% nitro. I still have 1-1/2
gallons of the stuff sitting downstairs - - - I don't know what I'll
do with it.
As I said, he got huffy when I asked questions regarding formulation
and oil quality. I asked him why every gallon was a slightly
different color, and he said that was *residue in the tank* from the
previous batch!!!! (which tells me that there's really no way to
know exactly *what* is in the fuel, if he doesn't clean the tank
between "batches".
Amazing.
Dennis T.

Marvin Denny called last night to see if I had actually performed the test he suggests and that I promised to do. I hadn't, so he beat me up about it. Or was it that joke Rich "von" Lopez and I played on him so many years ago?

At any rate, I take Marvin quite seriously on this sort of stuff, I'm not so sure we should just let the thread die a slow death.

Unfortunately, I came to discover that other than some YS 20/20 fuel in metal gallon cans, I have no unadulterated fuel in plastic bottles.

Look, it is said that all one needs to do is leave a fresh gallon of fuel alone for a day or so, siphon off the top 90% or so and then take a real close look at what remains in bottom of jug.

For his part, Marvin said he would be boiling off the volatile ingredients from a quart or so of fuel, this being the remnants of processing several gallons of factory-fresh fuel as per above procedure.

Too many posts and responses on this. Basically, I can only go back to what GMA has told me, "28% all-castor is what you use for the Fox 35". That is what I use, And SIG, and others make it. No problem, and vendors usually sell 28% castor fuel at contests. Percent nitro is not an issue. No excuse not to use it.

This is the first time I've visited this thread and I must say it is entertaining!

I've been flying model airplanes for over 40 years and I certainly hope I've learned to run ANY engine (I have about 200) on any commercially produced fuel with more than 18% lubricant, be it castor, synthetic, or a blend...without doing the engine harm.

I started mixing my own fuel in 1969 using Ucon synthetic straight and with castor blends without problems. The only reason I don't mix fuel anymore is that the quality and diversity of modern fuels is so much better than it was in the 60's and 70's.

If it is possible to make a Red Head McCoy into a "Black Head" in one flight, I'm surprized...more for blaming the lubrication than than putting the fault where it belongs.

Currell is right on the mark on this one!

Cheers,
Bob Edison
Anchorage