I am interested in reading your favorite fuel percents for fox .35 and similar engines. I think im going to have to mix some.

Byron Traditional 10% Nitro 20% Oil with castor added to bring oil content to 29% works very very well for my Fox 35 40th Ann.

Martin

15% nitro, 29% straight castor, rest methanol.

    Brett

If you use the above fuel blend, use... light... props, like wood ones, try to stay away from heavy plastic props 

You crank will appreicate it much !   

Randy

These three engines are pretty old. The crankshafts fit good and tight and the compression is great. I dont want to tear them up now. I have always flew 1\2a and jr. size stuff so i have never run them. I have had a S1A Ringmaster, mostly done, hanging on the wall for about twenty years. I finally finished it and am neer a test flight. 

Uh HUH  .. that is what Billy says when running 25% in them  :-)    ... Cranks  still  tremble wih fear 

  Fortunately someone thought of that problem, and came up with a solution. The source eludes me at the moment.

   If Billy is running 25%, better start making "high zoot" connecting rods, too - that's the next thing to go.

    Brett

Aero Tigers and HP 40s fortunately  cured  Billy's  FOX 35  woes by putting them in drawers instead of the Planes,
It was funny back in about 82 or 84 Billy met me at Lexington... you maybe was still in KY at that time...he had a nice dark blue Ares with a FOX 35, I was next to him filling and when he cranks the 35 you could smell a lot of what seemed to be  excessive NITRO in the air...I asked him how much was in the fuel..he just said "not enough"

   That wasn't the airplane he flew into the side of his toolbox, was it?

    Brett

   That wasn't the airplane he flew into the side of his toolbox, was it?

    Brett

NOT...at that  contest..

NOT...at that  contest..

  That was the only Lexington contest I saw Billy fly in before I moved out. As I recall the airplane that wound up in the side of the toolbox was black, not blue, and it didn't have a Fox. Maybe a Juno, it was about the right time.  Not a good day in Billy-world.

     At a later contest (82?) I also saw Jack Sheeks pancake an airplane inverted and have about a minute-long shaft run on his Como 51. Afterwards, it ran *a lot* better!  A 1.5-6 is a perfect break-in prop.

    Brett

While on the subject of fuel for Foxes, I can remember being told by a number of people that once a Fox has been run for a long time on straight castor, switching to a castor/synthetic blend would destroy the piston/liner seal and ruin the engine.

Since I believe that one test is worth one thousand expert opinions, I decided to research it. I had a substantial accumulation of Fox 29s and 35s that were very old and had been run on straight castor. The (Mehanite) pistons were, for the most part, black and on a few, the exhaust port was partially blocked with burnt-on carbon.
I took the worst of the lot and ran them on Powermaster 10/22, 50-50, fairly lean and at high speed. The color of all the pistons lightened, the carbon burned out of the exhaust ports and they all ran extremely well. Not one suffered any sort of performance breakdown. A few that had somewhat low compression to begin with remained that way as did those with excellent compression. 

Since there were a number of engines involved, I considered the test to be valid.
Since then, I have run Powermaster or Brodak fuel in ALL my glow engines, including some very old vintage engines and never looked back. I think that the hype about using only straight castor is a carry over form the past when it was the only viable lubricant. It may well be that any shortcomings associated with castor oil are mitigated by blending it with high quality synthetics.
Just my opinion.
Bob Z.

You guys are a hoot; I love these kind of threads that are informative as well as entertaining. I wish Brett would repost his bisquit making thread. I laughed till I cried.

You test is not really conclusive of anything, I am the one that wrote the statement you talk about, and the quote is this
 " Do not use the synthetic  blend in an old motor that has a lot of time on it with all Castor fuels; the synthetic will remove the Castor varnish off the piston and sleeve and will in some cases, leave you with the worn-out motor that had to start with."  

Note that the quote does not say that it WILL ruin ALL motors, it says, in SOME cases it will leave you with the worn out motor you had to start with. It is a fact, I have seen this several times  with my own eyes , and I have had it happen to a used gummed up motor that I bought years ago.
So what I wrote is a "fact", it happened to me and many other people.

It is obvious that the motors you had were not worn out, If you remove the thick coating on the side of a piston and sleeve that is badly carbon-gummed up , you can reduce the compression to a point the motor is no longer able to be started easy, and runs crappy..

And to expand, "not wearing out" is only one of the criteria. It also needs to run well. I ran lots and lots of Fox flights on 5%/20% blend that Lew McFarland mixed and sold, it ran pretty good and it lasted acceptably well (40+ gallons in actual stunt flights and it was still fine at the end). But it ran *way better* on Fox superfuel, and it ran *way better* on Lew's fuel when I added a bunch of castor. Others have run SIG unaltered, K&B 100, etc, with relatively low oil content with acceptable results. But I think it runs A LOT better with 29% oil. It has more power, generally.

....is crappy a word?

    If it isn't, it should be.

   Brett

First off - I don't like the implication that I'm lying. I know what I'm talking about and I proved what I set out to prove.
It is 100% conclusive. The pistons of ALL the engines were indeed black, some as I said had marginal compression, some were excellent. After runs with the blend, the pistons were much lighter in color but there was NO CHANGE in compression. What caused the change in color? I have no idea. BUT, if it was due to the removal of substantial carbon or varnish buildup, it would have surley reduced compression.
I also find it hard to beleive that a compression seal on an engine can come from built up or caked on varnish and then be damaged by a lubricant
The information I quoted did not come from you - I doubt that the fellows who told me even know you. It was probably around 15 years ago.
I spent enough years in research and development to stand by the quote about test versus opinion.
You just stated that synthetic blend WILL remove the castor varnish. Sounds like a statement of fact to me. Do tell, what tests did you perform to prove your statement?

Bob Z.

First off Bob, You brought this up by suggesting that someone who said this was lying, Suggesting that I was a liar, I didn't use that word , you did, I will stand by the "facts" I wrote.
I also stated that your engines must not have been worn or gummed that badly. I never said "all" engine would be ruined, or loose compression
The synthetics in the fuel I use will clean the burned on sludge from Castor off of pistons, and It will also clean the Castor burn out of ring grooves and rings. It will not happen immediately, it takes time, but it will clean the insides of engines.
Your test does not have any bearing on what happens to engines other than yours, You are trying to tell me that what I saw with my own eyes didn't exist. It did, and what I wrote is absolutely true.
Tell people what happened to your motors, don;t say others are not telling the truth about their findings.
By the way I have told people this for over 30 years, and have written several articles mentioning this for the past 2 decades.
I have had many of my customers and friends that have had rings stuck in the grooves by all castor fuel, and YES running a synthetic blend most of the time helped unstick the ring and helped the motor get back running well, without dissembling for cleaning, so  I would say ,yes, the blended fuel helped clean the ringed engines too.

Regards
Randy

"And to expand, "not wearing out" is only one of the criteria. It also needs to run well."

Correct , and most all motors I have seen run better if they are NOT badly carboned up, They work better when they are clean.
It also seems that ABC AAC ABN motors also run much much better if the pistons and sleeves are free of burned on carbon, and it seems to be more critical on these types than even the ring or lapped type engines.

   Absolutely, and I have had great luck with low oil content and synthetic on AAC, etc.  We started on the topic of Foxes, and all of mine ran *much* better on straight castor and lots of it. Adding 5% of oil gave it a much more power as adding 5% nitro.

   Brett

  That was the only Lexington contest I saw Billy fly in before I moved out. As I recall the airplane that wound up in the side of the toolbox was black, not blue, and it didn't have a Fox. Maybe a Juno, it was about the right time.  Not a good day in Billy-world.

     At a later contest (82?) I also saw Jack Sheeks pancake an airplane inverted and have about a minute-long shaft run on his Como 51. Afterwards, it ran *a lot* better!  A 1.5-6 is a perfect break-in prop.

    Brett

 You maybe right I think I remember hearing something about a Juno that had an unfortunate meeting with flight equipment...

Hate to see a plane lost for any reason but I cringe to think about hitting my own flight box, fuel can..etc..

Randy