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Old Nov 12, 2012, 11:13 AM
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United States, KY, Paducah
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.049 Fuel. . . and various questions

Hello all,
I have a Testor's McCoy .049 that I restored back in the spring (link to restoration). I have been wanting to start it ever since but have not had any fuel for it.

What kind of fuel do I need and where can I buy it?

Last time at was at my LHS they said they do not carry 1/2A engine fuel. Can I buy it online, if so where? I may go to the LHS today, if I do what should I look for when buying fuel?

I do have some Nitro fuel for another engine. The sticker on the jug says "2 & 4 cycle. . . .18% oil content. . . .10%Nitro" Would this fuel be fine to try and start the .049 with?


It's probably easy to tell I have never dealt with RC IC engines before.

Thanks in advance,
Nicholas Morgan
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Old Nov 12, 2012, 11:17 AM
Old Submariner
United States, WI, Milton
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1/2 A Fuel

Check towerhobbies.com, they have it.

Tom
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Old Nov 12, 2012, 12:18 PM
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1/2 A engines need around 30 % nitro and plenty of castor oil to start and run at their best. Glow plugs must be in good condition, new is best. Needle valve assemblies must be clean and clear. Tank centerline should be level with needle valve. Need to squirt a little fuel into the exhaust port to start. Needle valve shoud be three turns out to start, turn it in to slidhtly less than full rpm. Starting battery must light glow plug to a bright orange glow. Flip prop smartly like you mean it. If it has a starter spring use it. My ears still ring from running 1/2A's.
in my younger days.
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Old Nov 12, 2012, 12:23 PM
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It will run with your current fuel. but it must not have only synthetic oil in the mix. Castor is pretty well mandatory for those older .049s especially. Or at least some.
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Old Nov 12, 2012, 01:03 PM
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Quote:
Originally Posted by PyroMan View Post
Last time at was at my LHS they said they do not carry 1/2A engine fuel. Can I buy it online, if so where?

Nicholas Morgan
http://www.gcbmrc.com/

Many folks running 1/2A engines have used him as a source for high nitro/all castor fuels.
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Old Nov 12, 2012, 04:18 PM
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Quote:
Originally Posted by E-Challenged View Post
1/2 A engines need around 30 % nitro and plenty of castor oil to start and run at their best.
That's not true anymore, 1/2A engines comes in all varieties these days. It might have be valid once a upon a time for the cox engines and other engines of similar construction, like the McCoy .049 discussed here, but it is not a general fact anymore (if it ever was).

You don't need 30% nitro in your Norvel, Thunder Tiger, MP Jet, Picco zero, Brodak etc. The level of Nitro is selected depending on your compression ratio and prop load, not the size of the engine.
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Old Nov 12, 2012, 09:14 PM
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I use Sig Champion 25 fuel for Cox engines. All the Champions fuels have 20% total oil - 1/2 castor, 1/2 synthetic.
http://www.sigmfg.com/IndexText/SIGCF001.html
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Old Nov 12, 2012, 10:56 PM
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Thanks for all of the replies.

So far I'm thinking about getting this http://www3.towerhobbies.com/cgi-bin...?&I=LXEPD2&P=7

Where do you buy Sig Champion 25 fuel GliderJim (or anyone) ?
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Old Nov 13, 2012, 08:07 AM
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You can get it directly from Sig in pints, quarts, or gallons. I believe you used to be able to avoid any hazardous materials surcharges by buying the smaller sizes, but don't know if that still applies.

Their website doesn't allow you to link directly to the page you need, but it's under Field Equipment, then Fuel, then Airplanes.
http://www.sigmfg.com
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Old Nov 14, 2012, 09:28 AM
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Good info all, and it looks like you were careful cleaning it up.
The older engines had softer finishes and really need some castor to protect them. I typically ran .049’s on 15% nitro with 10% castor and 10% synthetic (though 25% nitro was easier to tune). The Tower Hobbies stuff is good (better be for $1 per flight). I've found Sig is better if you can get it.

I had a few swapmeet engines that were really gummed up when I got them but ran fine… for a while. Over a few flying sessions, they started to lose compression and power. While trying to troubleshoot, I looked into an exhaust port and they were squeaky clean inside… The synthetic oil (and who knows what other additives) had eaten away all the crucial glazing and varnish that was keeping the motor viable. Was a Powermaster blend… but I’m sure they changed their mix since ’93. The true 1/2A fuels are typically 20% pure castor, and definitly a better bet for an older small engine.
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Old Nov 14, 2012, 09:09 PM
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I've used Sig 25% nitro fuel, the one with Castor oil, and it is a solid runner for small engines.

I recently bought O'Donnell 30% nitro Heli fuel, through feedback. Then found their website that states it is all synth. I'm not going to lose any sleep over it.

For the Cox .049's, Bernie at Cox International has extra piston and cylinder combinations in case I wear one out. Those would not run as well if they had a build up of Castor in the cylinder walls.

In all cases, I think the thing that will ruin an engine in no time is overheating (running too big or too high pitch a prop) or running excessively lean. I like to tweak a touch rich and watch it lean out a little (not excessive, just right) in the air.

But you are right, to be on the safe side for older engines and plain bearing (not ball bearing) engines, a mixture that has Castor oil is a good safe bet.

YMMV.
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Old Nov 15, 2012, 12:06 AM
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The traditional construction with an iron piston in a steel bore needs castor oil, there is no question about it. The castor build up makes a protection layer and prevents direct metal to metal contact. Without this layer the engine wears out and the piston will not seal, there are numerous examples of people running with purely synthetic fuels in the old-school engines and it just doesn't work. Do your self a favor and use the contemporary fuel.
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Old Nov 15, 2012, 12:56 AM
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United States, KY, Paducah
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I haven't ordered any fuel yet, but I'm probably going to get some of the Sig fuel that GliderJim linked to because it is cheaper than the fuel at TowerHobbies. I'll let ya'll know when I place an order.

Quick question, somewhat off topic but I'm sure you guys will know the answer. Are companies still making engines this small today? If so who? Where does somebody buy a brand new .049 engine or smaller?

Thanks,
Nicholas
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Old Nov 15, 2012, 04:41 AM
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Oh yes... you're in the right forum for that.

Like OkiThumper mentioned, Cox International is where I get my small engines and supporting gear. There are a couple other shops too, but I've had only the best service from Bernie. The "modern" ones will do fine on a synthetic/castor mix of oils (modern is relative, it's a pretty old design) so long as you don't go too lean. I run 25% nitro buggy fuel in mine. Comes with 12% synthetic and I add enough castor to get 10% of each for 20% total oil content with about 22% nitro. Even if one burns out, replacement cylinders are cheap enough.

Smaller than .049... that's tricky. There are still .020 and .010 Cox motors around, but they haven't made one in a couple decades and glow heads are hard to come by. You can find PAW diesels too, but like the smallest Cox motors, they are prized by those who had one as a kid. Tend to be pricey.

Definitly run the McCoy a couple times. Then, maybe consider a new Cox engine to fly.

Cheers,
Vince L.
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Old Nov 15, 2012, 05:30 AM
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Quote:
Originally Posted by surfer_kris View Post
The traditional construction with an iron piston in a steel bore needs castor oil, there is no question about it. The castor build up makes a protection layer and prevents direct metal to metal contact. Without this layer the engine wears out and the piston will not seal, there are numerous examples of people running with purely synthetic fuels in the old-school engines and it just doesn't work. Do your self a favor and use the contemporary fuel.
Here we go again....

First: it is very possible, that if you are in the US, there is no suitable substitute for castor. That CAN be a fact....

Second: if an engine is "broken in" and operated on castor oil, it CAN fail when using synthetic.... that is also a very possible outcome if you take the wrong approach....

But the statement that an iron piston in a steel liner MUST be lubricated with castor, is just utter BS.
I have the Cox engines to prove it: I bought my TeeDee 051 20 years ago new in box (no idea how long it has been sitting in the store), has never seen castor, only car fuel of 16% Nitro and over, and still as good as the day I bought them new. And car fuel typically contains less than 15% oil.
I have one or two BabeBee 049 that I have also only run on car fuel (bought them used) and they are OK as well.

If an iron piston in a steel liner needs castor, than why doesn't an iron piston ring in a steel liner need it? After all, a piston ring has a way higher contact pressure to the liner than a piston....

If you need the deposits to prevent metal to metal contact, than Castor is not even an all that good lubricating oil, as it is the job of the lubricating oil to keep the metal surfaces apart, not the job of its deposits....

There are NO material combinations (within the range of useable materials of course, there is no oil that would lubricate a Lead piston in a Zinc liner ) that cannot be lubricated properly with a synthetic, although I admit, that these synthetics might not be availlable everywhere.

Castor oil has many beautiful properties, and the deposits that "protect" your engine are one of them. Unfortunately, these deposits indeed prevent metal to metal contact, and thus effectively stop the mating process of the running surfaces: your engine never gets really broken in, the imperfect surfces in stead get stuffed up.
That fact is what causes your engine to break down when you change over to synthetics without the proper precautions, not the lack of lubrication of synthetics, since in fact, synthetics are usually far better lubricants in every respect.

If you treat the engine as new regardless of its running hours on castor-fuel, and just give it a complete break in period they will run properly, provided you have a good synthetic oil.
Unfortunately, Cox states their engines only require a short break in (one or two tankfulls) but that is due to the residue forming: it doesn't break in any further as the residue arrests that process. On a synthetic oil, they just need the same break in period as any other engine, which can be up to two hours of running slobbering rich.

I have had several second hand bought engines of different brands and different material combinations break down on me within a few hours of operation, and i never understood why, since I have been breaking in all my new engines on that same synthetic, and running "castor-only" engines like the Cox also succesfully on Synthetics.
Then it dawned on me, that castor effectively stops the break-in process prematurely, and the synthetics wash away the residues, leaving me with an only partially broken in engine that I was just using as if it was fully broken in.
Since then, I have treated all second hand engines, regardless of running hours, as new engines, giving them a full break in period, and never lost an engine since.

It is up to the OP, to figure out which oil is availlable to him, and it is very well possible, Castor is the best option to him, but the statement that a Cox can only be lubricated with Castor, is just an uncomplete and not 100% correct statement. If you have access to for example Carbulin, and you give the Cox a good break in period, it will run just as well on that.

Brgds, Bert
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