I recently bought a Cox .049 engine from ebay and before I put this on my first C/L model I need to know some things. What fuel does it take? How do I remove the head? What's the hole on top of the back plate for? and How do I tune it?

http://reviews.ebay.com/Cox-049-Oper...00000005479141

Here's a scan of Cox's General Starting Instructions. I had to reduce them but I hope you can still read it.

Click on them, then right click on it to save to your desktop. After you save them you can open them and zoom on them like a picture to make it easier to read plus you'll have the copies saved on your PC for yourself.

Learning to start them takes a little patience, but it's easy after you know how and they can start on the first flick usually.

If your starting it with a bare finger, sand the prop a little to remove the sharp mold flash on the flipping edge of the prop. Finger cuts and fuel is a wicked combination nobody should have to experience.[:@]

I should mention the key to getting one to start well for you is to be absolutely sure the glow plug stays well lit.

The pictured engine is obviously an engine removed from one of the many many that cox provided for various vehicles along their toy road.
It looks like the fuel enters from an outside tank through the black fuel line. It looks like the long stem on top is a form of needle valve.
To change glow heads, notice the small indention on the silver glow head (one each side). That is for using a cox engine tool to unscrew the glow head. Without such tool, I have found that a nice pair of needle nose pliers, properly applied, can perform such task. There should be a copper gasket under the head. Use care to save it.

A tip that is seldom advertised or spoken of, is that small engines like a lot of cooling oil. Most users speak of the requirement for high nitro. That is incorrect as far as the "NEED". The standard cox .049 is very happy with a 10% nitro, and at least 20% castor oil. I have 3 that I have been flying with, kids using my original design models ranging from 18" w/s to 24" w/s, two being almost 20 years old and one only 8 years old. They start easily with the spring starters, are easy to needle using the stated fuel (old ducted fan engine fuel) and run very well, certainly well enough for sport use.

The hole at the top of the backplate is called the snorkle tube-holding your finger over it while hand turning the prop will help prime the engine[8D]

Thanks, I just need to know one more thing though, why is there a hole on the support behind the knob? I think its the air intake but I'm not sure.

Yes, 509boatman55 just answered that. He called it the snorkle tube, which makes sense if you know that the normal air intake for plastic-backed Cox engines is in the center of the backplate. This one has the intake extended up toward the needle valve in a snorkle-like fashion.

Have fun!

3D 4 ME,

The engine was installed in some RTF planes and was also sold separately as the "Sure Start".

Check out Blackhawk Models, they are just now introducing some CL planes specificly designed for that engine.

George

Oh, I didn't see that before. Thanks.

I have a feeling that mine was mounted on a PT-19, when I recieved the engine it had a yellow firewall on the back. Thanks for the info.

I figured as much. Thank you.

#D 4 ME,

Go to the 1/2A forum. Here's all your answers.

Heres a link the the thread http://www.rcuniverse.com/forum/m_3747940/tm.htm

Thanks

Thanks for your info

__________________
NATHALIE
online jobs

Small engines give off their heat very quickly and DO need higher nitro fuel to keep the temp up. Cox standard blue can fuel was 25% nitro and the red can racing fuel was 35% nitro. Both use 20 castor oil. They will run on 10% but don't like it. World of difference with high nitro. K%B made Super Sonic 1000 with 25 % nitro for 1/2 A engines.

Here in the US we naturally use fuel with nitro but there are many countries where you simply cannot do this and they run theirs on zero nitro. Hard for me to imagine but they do it because they have to or else go diesel.

Robert

And here in the US is where most of Cox engines were sold. Physics overrides location and price of fuel in the use of model engines. Small engines give off their heat very quickly and the use of high nitro fuel is required for maximum reliable performance. that's why Cox made their fuel at those nitro percentages and why other companies made high nitro fuels in small 1/2 pint cans. Strictly for use in 1/2A engines. Yes a 1/2A engine will run on FAI fuel but lousy. You'd have to increase the compression ratio and that's a bit difficult to do.

I recommend you get one of Clarence Lee's or Dave Gierke's books on the model airplane engine and see what they write about small engines and nitromethane.

Also, I lived in Japan for 4 years where nitro was very expensive. Even they ran their little engines on high nitro fuel. If you ever get your hands on an Enya 049, look what the manufacturer recommends for fuel.

Someone reported on another thread that later Cox fuels contained 15% (standard) and 25% (racing). I believe that person said Cox also dropped down to 18% castor.

I read in a model mag that tests revealed that 20%-22% lube runs better. I try to keep my lube in that range.

I have used 5% nitro and although it will run needle adjustments get much better at 10% and even better at 15%. I would keep it between 15% and 25% unless you are competing, then up to 35% is OK. I usually use 15%.

Another consideration is lube. Cox engines running hot (high nitro) will form varnish if all-castor lube is used. Many of us had to run an occasional run of a "special" fuel containing gun cleaner which, at the time, contained nitro benzine. Occasionally you would need to tear down the engine and clean the piston and cylinder with a brillo pad or gun cleaner. Adding some synthetic keeps it running cleaner. A few use all-synthetic successfully while others (myself included) believe the ball socket needs castor to survive.

If you run them in competition you will probably run them harder and not expect them to last as long. Which brings up the reset tool. You should keep the ball socket running with very little slop. The harder you run, the more often you need to reset.

For sport flying, you may only need to reset once. If this is the case, you might consider finding a friend who has a reset tool to help you. They are hardly worth the cost to reset once or twice. Make sure you learn to do it properly.

George