black window questions

TheBear Mon Jun 06, 2011 5:18 pm

Hi everyone I have a question concerning the cox black widow I had a friend give me one for the purpose of teaching my 11 year old step son. Looking online I have come to discover it is a black widow black case, black fuel tank, spring start, and a red nose cone. My question is why does it have 2 fuel tank fill spots one on top and one on bottom . Also which position the needle should be in in relation to the cylinder head. Thanks guys also checking coxengines.ca they have an oem one that the pictures show both top and bottom tank inlet on

nitroairplane Tue Jun 07, 2011 1:27 am

Well the reason for two holes is that one is actually a vent but the tank can be filled with either the needle valve should be 3 or 4 turns out.
Here is how I start mine I am not sure how much you already know so please do not be offended by this simplified reply.
1. Make sure that engine is securly mounted to a suitable test platform like a piece of wood or test stand.
2. Fill the tank it is full when fuel starts to come out of the vent.
3. Close the needle valve all the way and the turn it out 4 turns.
4.prime the engine by putting a little fuel on the piston side at the exhaust ports then connect the glowplug clip.
5. Engage the spring starter and release if the engine solitudes and coughs ou fuel turn in the needle valve so that it is so far in that the engine will bearly run and the turn it out 1/2 or 3/4 of a turn out as this will be a good starting point for fine tuning or just leave it there if you are happy with it.
About fuel if you don't already know the fuel must be at least 20% castor oil and I find 25% nitro is good.
Regards,
nitroairplane

TheBear Tue Jun 07, 2011 10:33 am

Thank you for your response and am in know way offended by you breaking this down barney style for me. After digging around this forum I found a link to an admins Google site which had the instruction manual for me. Saw how to take this motor apart and learned the fill tube is set up so the over flow goes from the bottom of the tank all the the way to the top. The back plate was actually turned 90 degrees this was so the pick up tube would be at the bottom of the tank. Next step is to call the hobby shop and find out if they have a prop glow plugs fuel and a battery clip. If they don't have the fuel guess ill be making it myself to make sure I get the 20% Castro oil

nitroairplane Tue Jun 07, 2011 11:02 am

The fuel that i recommend is sig champion 25 you might as well get the rest for coxinternational as they have the lowest prices and are good guys who also give great advice.

EXModelEngines Wed Jun 08, 2011 10:30 am

Yes, I would also recommend the Sig Champion 25% as well. It has a good balance for all around flying. If you going to be doing high RPM flying adding another cap-full of castor oil wouldn't hurt.

If your going to make your own I would use the following mix:
Methanol: 65%
Nitro Methane: 15%
Castor Oil: 20%

You can even reduce the castor 2 to 4 percent and replace with KLOTZ Lube, I think it was KL-201. I believe Cox used this in the late 60's in their own fuel mixes.

Regards, Matt.

nitroairplane Thu Jun 09, 2011 1:59 am

I think that Cox did use klotz but I may have bennol all I remember is the fuel was a sort of red at one point or this may have been testors but weren't they once the same company.
Regards
nitroairplane

EXModelEngines Thu Jun 09, 2011 11:43 am

Yeah, I think that was the Testors or possibly K&B?

I'm not sure, but I remember hearing that one of the fuels had an interesting shoe polish smell.

Matt.

nitroairplane Thu Jun 09, 2011 12:13 pm

Yeah i just checked it is Testors i confirmed it as when i watched a control line video on you tube there was some bottles of Testors fuel shown.

gcb Fri Aug 12, 2011 3:28 pm

EXModelEngines wrote:Yeah, I think that was the Testors or possibly K&B?
I'm not sure, but I remember hearing that one of the fuels had an interesting shoe polish smell.
Matt.

Testors 39 was a popular fuel in the mid nineteen fifties but apparently had insufficient lube. Now extinct.

K&B was always known as a good fuel. Originally all castor, they expanded their line to include a synthetic lube that they called X2C. Not sure if it's still available.

The shoe polish smell was from fuels containing nitro benzene. The benzene was dropped when it became known as a carcinogen (sp?). I think this was mostly in Francisco fuels. This is a fuzzy area as I was just getting into modeling as these were being phased out. I was a kid.

George

SuperDave Sat Aug 13, 2011 7:35 pm

The needle valve is located directly behind the cylinder.

All of my Coxes run great on Sig 25 fuel. Running higher nitro shortens engine sevice life.

SuperDave

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