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Small engines big hassle

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Engine Doctor12/10/2017 09:55:10
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1812 forum posts
4 photos

Yes you can still buy new Cox engines but the new engines are rubbish compared to the older models. Cox collectors will probably pay what looks to be very high prices for engines if they are original Cox's and not the later offerings . It's similar with other engines like ED diesels. Weston UK can supply a few models new but you occasionally see them make stupid money ,far more than new from Alan on sites like eBay and silly asking prices at swap meets. Like all our old engines the value is driven partly by nostalgia and partly by rarity but they are only worth what someone is willing to pay. $90 for the black widow in the link even a proper Cox is a steep price but if someone is stupid enough to pay it then good luck to the seller.

Piers Bowlan12/10/2017 19:51:54
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1033 forum posts
28 photos

Did somebody actually buy the $90 Black Widow? I think some people just keep putting their wares on these auction sites for silly prices in the hope that some mug will eventually buy it.

brokenenglish12/10/2017 20:32:55
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249 forum posts
21 photos
Posted by Piers Bowlan on 12/10/2017 19:51:54:

Did somebody actually buy the $90 Black Widow?

Not yet Piers. It's still on sale at the moment.

With the selling format adopted, I think the guy will leave it on sale for a week or two, and then let it go for the best offer he receives, but we won't have any way of knowing what the actual sale price was ...

onetenor12/10/2017 21:54:15
1366 forum posts

£65 if converted .Seems fairer compared to the price of "NEW" rubbish models.Providing it is original of course.

onetenor13/10/2017 00:04:11
1366 forum posts
Posted by Piers Bowlan on 08/10/2017 13:55:00:

Yes that would do it Bert but I fear the model might rotate faster than the prop - but not for very long!

As you can see, the reed valve is held in place by a spring and is easily removed and cleaned in meths or similar. As has been said earlier, remove and clean the needle valve and spray carb-cleaner or meths down the orifice to get rid of congealed fuel/oil and foreign matter. There is not much to go wrong so if the fuel is at least 15% nitro, fresh and you have a decent glow from the plug it should start and continue to run. Hard to believe that such a small engine can make such a loud irritating noise! I spent a lot of my misspent youth playing with these great little engines One way to clean jets is with a canister of gas used to refill lighters. Works a treat. You might have to play with fuel tubing to use as adapters to get gas into the NVA/ A pre soak in Amyl Acetate or Acetone helps a lot. If you apply some to the reed valve with an artists brush dismantling may not be needed.

 

 

Edited By onetenor on 13/10/2017 00:10:16

Piers Bowlan13/10/2017 04:42:51
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1033 forum posts
28 photos

It takes only a moment onetenor, to pull the spring out with a pair of thin nosed pliers and a pin to gently lift the reed valve to clean it, if it is gummed up. Just don't bend it!

Just curious, why are the 'NEW' rubbish models, rubbish? Is it the tolerances, materials used or general build quality?

ken anderson.13/10/2017 10:10:23
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7863 forum posts
712 photos

new model for Cox engine...cheap etc.... smiley

ken Anderson...ne..1..... rag dept.

bert baker13/10/2017 10:44:10
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895 forum posts
192 photos

I may have a go at converting a head to standard plugimg_1586.jpg

bert baker13/10/2017 10:46:11
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895 forum posts
192 photos

Can I upload video to this posted

brokenenglish13/10/2017 11:25:09
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249 forum posts
21 photos
Posted by bert baker on 13/10/2017 10:44:10:

I may have a go at converting a head to standard plug

Bert, I think you can buy them from the present Cox engine suppliers but, for me, none of these "reed valve in the tank" engines are worth messing with.

Piers Bowlan13/10/2017 14:12:03
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1033 forum posts
28 photos

Erm... Why?

Engine Doctor13/10/2017 14:17:12
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1812 forum posts
4 photos
Posted by bert baker on 13/10/2017 10:44:10:

I may have a go at converting a head to standard plugimg_1586.jpg

you will need an old cylinder/barrel to screw the head into to hold it while tapping thread for normal glow plug and to protect the fine thread for the head to barrel joint .A lathe really does come in handy for this.

bert baker13/10/2017 14:47:33
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895 forum posts
192 photos

I have today had a go at getting them all to run,

The one that has front induction works but wont peak out, but is sporting a bigger prop than the others

The other two,

Well i held both nose down and put a little fuel on the air filter mesh on both and turned the prop and both pulled the fuel in and didn't try to squirt it back out.

I then primed them and both ran for a longer time than just priming through the port,

I have rechecked the fuel needle and its seat in the tank,

I am suspecting the spring that is fitted to the fuel pick up pipe,

I have removed it cleaned out with a pin and refitted it.

brokenenglish13/10/2017 21:25:14
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249 forum posts
21 photos

Bert, I think Piers asked why I thought these reed valve engines are not worth messing with. Well, they're unpredictable and it's difficult to achieve consistent runs. There's very little flexibility, no real idle or slow running possibility. Even if they're "set rich", they still scream when the fuel runs out. Honestly, their only virtue is that they're cheap!

Could I offer this video, as a "Small engine - No hassle". Have a look, and then reconsider whether it's worth messing with a reed valve 049.

 

 

Edited By brokenenglish on 13/10/2017 21:27:17

Piers Bowlan17/10/2017 06:28:08
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1033 forum posts
28 photos

Ah OK, I understand now! The 049 reed valve engines have two throttle settings, 'screaming' and stop, they just don't do idle or slow running. They were made for the C/L and FF era, climb and glide type of flying. If you want an RC throttle fit the Paw 100 in the vid (very nice) or OS 10 or 15 glow, depending on whether you prefer the smell of burnt ether or nitro in the morning. If you like neither, go electric!

Bob Cotsford17/10/2017 15:16:09
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6834 forum posts
366 photos

IIRC they did a 'throttle' for the .049 reed valve jobs but I think it was an exhaust strangler - for some reason they didn't catch on teeth 2. As Piers said, they were great for c/l, ff or single channel where they were pretty reliable. 2-3 minutes of full power was often more than long enough.

Peter Christy17/10/2017 16:45:55
808 forum posts
Posted by Bob Cotsford on 17/10/2017 15:16:09:

IIRC they did a 'throttle' for the .049 reed valve jobs but I think it was an exhaust strangler - for some reason they didn't catch on teeth 2. As Piers said, they were great for c/l, ff or single channel where they were pretty reliable. 2-3 minutes of full power was often more than long enough.

I still fly a pair of single-channel models with .049s, and yes, 3 mins of full chat is more than enough!

There was a "proper" carb made for Cox's by Tarno. I actually have an unused Tarno carb somewhere in my junk boxes. I believe they didn't work very well without a muffler to provide some back pressure. The basic carb is designed to screw into the inlet of a TeeDee, but I've also got an adapter to make it a rear mount for a reed valve engine with an external tank. I must confess that I've been thinking of building a tiny "full-house" Cox powered aerobat for a while, but other projects always seem to get in the way.....

A note to the OP: Cox's do NOT like being over-propped! They like to scream! You wouldn't try and pull a Ferrari away from rest in 2nd or 3rd gear, and similarly, don't expect a Cox to run properly with a large prop! wink

--

Pete

bert baker17/10/2017 18:51:30
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895 forum posts
192 photos

My little AE 0.5cc runs nice,why can't the Cox do the same img_1596.jpg

ted hughes17/10/2017 21:03:37
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453 forum posts

Cox International usually have a lot of spares:**LINK**

Peter Christy17/10/2017 22:11:24
808 forum posts
Posted by bert baker on 17/10/2017 18:51:30:

My little AE 0.5cc runs nice,why can't the Cox do the same

Diesels are usually quite happy swinging bigger props. Cox engines like to rev! Small props and lots of nitro are usually the answer! wink

--

Pete

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