fun scavenger hunt

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I remember back when that model was introduced. A rear exhaust engine, if I remember correctly.

It was an advanced engine design that was a little ahead of its time. It did not help that it was still based upon the "must use castor oil" paradigm, that Fox later began to rescind. It was too little, too late. Fox had a good ride for a short while, but the need for castor oil made their ride short. Clubs started buying fuel by the barrel and most times, that fuel did not contain enough castor oil to keep Fox engines healthy.

Not long after that, K&B brought out their 1.00 Aero engine. Also rear exhaust with an in cowl muffler that was built into the engine mount.

Ed Cregger

;^) Yeah but it wasn't a Fox... I've a K&B 3.5 motor in the garage. Has the sleeve and piston for the boat motor, currently resides in a vintage Associated RC300BD. Really ought to find new tires for it and find a SMOOTH parking lot. Something of as a rare commodity as the car it's self. Another castor motor in the stable.

I wont mention the TeeDee 049 with the davis diesel conversion...another motor needing homebrew and pleanty of castor. What is it with me and motors that require castor oil...must be something wrong with me.

-- Keith

;^) Yeah but it wasn't a Fox... I've a K&B 3.5 motor in the garage. Has the sleeve and piston for the boat motor, currently resides in a vintage Associated RC300BD. Really ought to find new tires for it and find a SMOOTH parking lot. Something of as a rare commodity as the car it's self. Another castor motor in the stable.

I wont mention the TeeDee 049 with the davis diesel conversion...another motor needing homebrew and pleanty of castor. What is it with me and motors that require castor oil...must be something wrong with me.

-- Keith

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Well, to me, all glow engines need castor oil.

Ed Cregger

Maybe I should have said "drinks" castor oil? but I agree with you. Castor just has better lubricity properties at high heat and gives a little more cushion in lean conditions iirc. I am rebuilding a

72' Suzuki T-500 Titan. A 2smoke bike with oil injection...sure wish I knew how to convert the oil pump to handle castor or somebody who does it. I WONT do like many others have/did and remove the oil pump and switch to premix. Can you imagine try to do that at the gas pump? LOL I don't think so. Gotta go batten the hatches, have a blizzard warning and cautious sort that I am I haven't slept a wink.

-- Keith

Note : No model engine *needs* castor oil. What it will do is save it from a lean run if you muff up the needle settings.

Some model engines were designed without bushings in the connecting rod and truly did "need" castor oil, unless a very limited lifespan was acceptable.

Ed Cregger

hmm, though i'd mentioned that already...

-- keith

I think its more of a question of it being an oil with properties you couldn't match with synthetics for a long time.

You can now, but whether such oils are available or cheap, I do not know.

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And that is the problem here in the US. It is my understanding that Cooper Fuels is offering a synthetic that, if not the same, is comparable to the good synthetic oil that is available in Europe.

Problem is, I haven't used it yet, nor do I know anyone else that has.

Ed Cregger

Am I wrong in assuming that part of the protective properties of castor oil was the "varnish"( for lack of a better word) coating it left on parts? New oils can do that? mk willing to be wrong again........

"The Natural Philosopher" wrote

When I first started in RC, I had a .40 Fox ABC deluxe. I tried it without special castor oil fuel, and it never seemed to get as many RPM as other people's .40's.

I read the book on it, and decided to follow the advise on having castor oil in the fuel, so I found some straight fuel grade castor and bought a bottle.

The club had fuel convenient to buy, so I would get a gallon of that, and add 2 or 3 ounces of my castor to the gallon. Problem solved.

I have run extra castor oil in my fuel, since then. Engines that sit for a long time still do not rust, even without using after run treatment. I swear by it.

Cheap insurance, and I get that nice smell, as a bonus!

"MJKolodziej" wrote

I think you might be wrong again.

Really, I am no expert witness, but my understanding is that the large advantage of castor oil is the fact that its molecules do not break apart, until it gets much hotter than the temperature that synthetic fuels break down. It is the long chain molecules that give the lubricants their lubricating qualities, from what I understand. (simplified explanation, with much hand waving, here)

Also, the fact that castor is better protecting against corrosion in a sitting engine comes from the fact that castor gets thicker (think viscosity) at room temperatures, and does not run off the parts leaving them exposed to the air and moisture. Also, that it is not hygroscopic. (I think that is the word that means it does not attract water)

And I am also willing to be proven wrong, too!

"MJKolodziej" wrote

I think the vanish is simply a bad side effect, rather than protection. It is true that some of the castor does bake down into sleeves, and promote less friction. Kinda' like seasoning a cast iron frying pan.

yeah. Thats my understanding too. Oil have to not tear apart uder high temps and high shear, and not turn into glue at low temps either. Its a tough call and for a long time castor oil was the one to beat, but they beat it in the 60;'s ad its not been used in racing since then. I'd probably try one of the synth 2-stroke i;s that allow very low oil concentrations if I still had any model ic engines, but I dont ;-)

dunno about all that.

Hi Ed,

How does castor oil help with this type of bearing ? AIUI synthetics are "slipperier" lubricants than castor anyway so I'd have thought a plain bearing would be better off with one of those ?

I think the thing is that castor oil has always worked well in high temperature limited oil feed situations. Nowadays its not the only oil that does, but unless you know what oil to replace it with, stick to castor if its served you well.

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Besides the higher temperature tolerance of castor oil, it is also thicker in viscosity. It is also prone to sticking to surfaces instead of running off. Combining these two characteristics helps the plain bearing engine using castor oil avoid metal-to-metal contact.

Ed Cregger

and it smells good when you cook it through a glow engine. ;-)

I once got some test data and pictures from Bob Adkins (from the heart of Cajun Country) He polished up some large nails, and then dipped them in various fuel mixtures and hung them up to dry in a shed.

Once you reach a certain concentration of castor oil, the nail was protected from rust for a LONG time because the castor did not drip off and leave the metal exposed. The same characteristics that make it a good lube (persistence of oil film) and protecting a running engine, also help protect your engines when they aren't running.

I'll butt back out now ;-)

"Schiffner" wrote

Maybe I should have said "drinks" castor oil? but I agree with you. Castor just has better lubricity properties at high heat and gives a little more cushion in lean conditions iirc. I am rebuilding a

72' Suzuki T-500 Titan. A 2smoke bike with oil injection...sure wish I knew how to convert the oil pump to handle castor or somebody who does it. I WONT do like many others have/did and remove the oil pump and switch to premix. Can you imagine try to do that at the gas pump? LOL I don't think so. Gotta go batten the hatches, have a blizzard warning and cautious sort that I am I haven't slept a wink.

-- Keith

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I used to do it at the gas pump. I always tried to err on the side of too much oil, but it wasn't castor oil. That could make a real mess.

Who could forget the Suzy Titan 500cc twin two-stroke? I always wanted one of those, but never got to test ride one. They looked slow. I learned later that they were not even remotely slow. Granted, they weren't a Yamaha two-stroke, but the Suzy was no slouch.

Ed Cregger