Small engines big hassle

[Peter Miller]

Den's Model Supplies does Cox spares including heads for ordinary gloplugs etc.

I have happily run Cox .049s on Model Technics Formula Irvine Contest fuel That is 10% nitro.

[Doug Campbell]

Bert,

If it runs for a few seconds and stops it is probably a fuel blockage. These Cox Pee Wees are prone to it if stored for a time. Screw the needle valve right out and force some fuel down the whole to give it a good flush. Try starting it with the needle valve quite a bit more open than normal and you should get a run out of it, screw in the needle valve as it clears fully. This could take 2 or 3 tank fulls. The fuel you are using is perfect for these engines.

Doug

[bert baker]

Many thanks, I suspect you are right as it runs for short period after prime through port,

[Engine Doctor]

Posted by onetenor on 08/10/2017 12:54:52:

All that has been said is true but no one mentioned that the reed valve can stick. You would have to find instructions for strip down but not sure where.Re the heads I converted one of mine to take a plug. Drift the insert out from inside then carefully tap using Model engineering tap .24TPI but can't recall diameter. but is dia of glow plug. Use first and second taps. Don't run them both right through. On second tap go in stages trying the plug for fit. I can look for taps if no one can tell us what size is.

 P.S. That plane would qualify for an ebenezer contest .

Edited By onetenor on 08/10/2017 13:02:57

Hi OneTennor. The thread size for normal glow plugs is 1/4 x32 ME .  I find Converted heads for Cox engines usually result in a slight drop in revs ,approx 500 rpm. Southern model craft do 15 or 20% castor fuel that these engines love. I don't usually use or like castor oil based fuels but Cox's do like it. It's the castor oil that sets in the needle valve etc that causes difficult starts after a lay up. When reassembling most Cox engines no need to worry about piston direction as most are mounted on a ball joint instead of a gudgeon pin. 

[extra slim]

Sound advice already given, I would lean towards the reed valve.. very common for them to become brittle.. take out and soak/clean.. or try and get a new one.. flushing needle is also a common cure, but more often that not, it is the valve..

[bert baker]

I have found the original box and instructions,all advice given compliments the manufacturers recommendations.

I have cleaned all the 020 engines and checked all valves,they did rotate as per instructions.

My glow clip is home made but doesn't suffer loss of power through cables.

All th 049 engines always work, 

Edited By bert baker on 10/10/2017 11:08:41

[bert baker]

[bert baker]

[bert baker]

[Mike Stevens]

I have a black widow which i think fetch a few pence these days.....

[brokenenglish]

Posted by Mike Stevens on 11/10/2017 16:19:39:

I have a black widow which i think fetch a few pence these days.....

Sounds a bit optimistic to me. No Cox reed valve engine is of any great value.

[Mike Stevens]

**LINK**

[brokenenglish]

Posted by Mike Stevens on 12/10/2017 06:03:32:

**LINK**

Mike, that's an optimistic "asking price", with an invitation for lower offers.

A Cox engines collector might pay a reasonable sum for this "new in box" example, but I don't think he'll get his asking price, it's just not rare enough.

[Alan Gorham_]

I think many people don't realise that new Cox engines are still available at reasonable prices...

The Black Widow linked to above on sale for 90 USD could be bought new for half that:

**LINK**

[Bert]

Posted by brokenenglish on 11/10/2017 19:39:10:

Posted by Mike Stevens on 11/10/2017 16:19:39:

I have a black widow which i think fetch a few pence these days.....

Sounds a bit optimistic to me. No Cox reed valve engine is of any great value.

The early engines like the Thermal Hopper and Space Hopper have a reasonable value. Not nearly as much as that seller was asking, though. The later reed engines were made and purchased in such numbers that they can never be worth much. I got a couple of Black Widows in a job lot for £15 and that included a few other things I wanted.

Bert

[Engine Doctor]

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 Bowlan]

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.

[brokenenglish]

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 ...

[onetenor]

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

[onetenor]

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 Bowlan]

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.]

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

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

[bert baker]

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

[bert baker]

Can I upload video to this posted

[brokenenglish]

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.