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Cox Engine of The Month
December-2017
1/2A Nut's

"Chrome Moly TD .020 RC"



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Thanks again rsv1cox "Bob"

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Thanks again rsv1cox "Bob"

Post  roddie on Mon Oct 09, 2017 6:27 pm

Bob had recently sent me some "parts-engines" that he thought I might be able to use to get my Testors/McCoy .049 repaired. Bob threw-in a few other engines as well. Three of them were Cox .049 reed-valve engines. Today I got curious about their condition(s).

This one was a little stiff/sticky.. and is an odd mix of parts.. but was complete except for a needle-spring. The glowhead looked brand-new.. and was loose enough to remove by hand. There were x2 gaskets installed under it. Black-anodized (or painted) case.. with round drive-plate, early horseshoe-style backplate with aluminum needle and a copper-star reed.



#1 cylinder..



I oiled it with some very light "instrument-oil".. and she loosened-up with excellent compression. I pulled the backplate, smoothed-out the case over some 600 grit paper.. and freed-up the reed. The needle needed a spring.. so I got out my compression-spring jar and found one that should work.



This engine should now be ready to run! It came with a nice Tornado 6 x 3 prop mounted.

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Re: Thanks again rsv1cox "Bob"

Post  Oldenginerod on Mon Oct 09, 2017 7:11 pm

Roddie. Looking at your bottom picture, the spray hole is looking right out at ya. The tube (spray bar) will need to be reversed in the backplate, with the spray hole pointing at the reed. Looks like it might be a Black Widow with the tank swapped.
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Re: Thanks again rsv1cox "Bob"

Post  1/2A Nut on Mon Oct 09, 2017 7:16 pm

Take a look at this pic the engine is not ready to run Paranoid

Hats Off


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Re: Thanks again rsv1cox "Bob"

Post  pkrankow on Mon Oct 09, 2017 7:57 pm

It is the high performance pressure bladder arrangement


Devil
No

I jest, of course.

Phil
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Re: Thanks again rsv1cox "Bob"

Post  dckrsn on Mon Oct 09, 2017 7:59 pm

Somewhere around here, I have a backplate with the
spraybar drilled clean through. I forget  whether was a
product or postage stamp plate.
Bob
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Re: Thanks again rsv1cox "Bob"

Post  roddie on Tue Oct 10, 2017 12:03 am

1/2A Nut wrote:Take a look at this pic the engine is not ready to run Paranoid

Hats Off



dckrsn wrote:Somewhere around here, I have a backplate with the
spraybar drilled clean through. I forget whether was a
product or postage stamp plate.
Bob

It seems to me that I've also seen that.... but I can't dispute the fact that this one's in there backwards. I only had two other horseshoe backplates to check, which do NOT have mesh-screens on the air-intake. One is a red high-flow "Killer Bee" clone.. and the other is almost identical to this one in question.. (white-plastic with an aluminum needle).

Here's the other white one..




That pretty-much confirms it.. I just checked a "postie".. and it's the same.. and has only one spray-hole. Same with the high-flow back-plate.

I hadn't removed the reed from Bob's engine.. because it seemed to operate properly. Had I done that.. or taken a look at this other backplate; I might have noticed it. Rolling Eyes

I've never removed a spray-bar from one of these.. but I guess I'm gonna' have to try it. I would assume that I should try to align the "splines" when pressing it back in? I've read about swapping-in a fine-thread NVA, so maybe this will be good practice for when that time comes..

Anyway...... "THANKS" for saving me some grief, because I was anxious to bench-run it later-on today.



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spraybar R & R

Post  roddie on Tue Oct 10, 2017 1:14 am



Another handy use for the K & S assorted cut-offs I got through Tower Hobbies. A 1/4" dia. x 3/4"L. solid brass rod was the perfect size for pressing-out the spray-bar in my bench-vise.






not perfectly-centered.. but close enough..




Not a tough job at all.. Smile
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Re: Thanks again rsv1cox "Bob"

Post  Oldenginerod on Tue Oct 10, 2017 7:03 am

roddie wrote:
not perfectly-centered.. but close enough..



There are those who will tell you that there is an optimal angle for the spray hole to be on, which is not "perfectly-centered".
Some claim 15 degrees from perpendicular to the air flow for a Cox engine.

Personally, knowing full-well that we have discussed this at length before, uncovering a plethora of opinions, I would put it as close to centre as I could, being the position that I have personally witnessed most factory installations to use.
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Re: Thanks again rsv1cox "Bob"

Post  roddie on Tue Oct 10, 2017 11:57 am

Oldenginerod wrote:

There are those who will tell you that there is an optimal angle for the spray hole to be on, which is not "perfectly-centered".
Some claim 15 degrees from perpendicular to the air flow for a Cox engine.

Personally, knowing full-well that we have discussed this at length before, uncovering a plethora of opinions, I would put it as close to centre as I could, being the position that I have personally witnessed most factory installations to use.


Yes, I remember some conversation about that. Allow me to inject my own thoughts and blabber on this subject.. Laughing

Being that the tanked reedies' non-obstructing fuel spray-hole is exactly perpendicular to the airflow, there's probably some logic there. The product (tank-less) back-plate is a different animal though. What puzzles me is; the tanked engines' venturi-shape is the reverse of a conventional velocity-stack. Maybe it has to be, because of the fuel-jet's location? Turbulent-airflow occurs immediately as it enters the backplate and fuel-atomization is probably further enhanced by a pressure-wave produced by the megaphone-effect as it approaches the reed.

The product (tank-less) back-plate has to rely more on the spray-bar to augment laminar-flow into turbulent-flow for fuel-atomization.. but has the advantage of flowing a higher volume.

Whatever the case.. there's no disputing that these little engines are engineering marvels! Small Cox Logo



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Re: Thanks again rsv1cox "Bob"

Post  rsv1cox on Tue Oct 10, 2017 12:28 pm

It seems I got all those engines in the right hands, I know that you guys are enjoying them.

Many came with other engines, lets say Enya's Smile as a package and I just set them aside. I still have scads to clean up, if I start now, maybe by Christmas next year. Smile
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Re: Thanks again rsv1cox "Bob"

Post  fredvon4 on Tue Oct 10, 2017 2:24 pm

Gone for a while now but the kid in Noosa Australia got a bunch of my similarly acquired engines

I still have a box full of questionable engine stuff from LOT buys...
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Re: Thanks again rsv1cox "Bob"

Post  roddie on Thu Oct 12, 2017 9:52 pm

rsv1cox wrote:It seems I got all those engines in the right hands, I know that you guys are enjoying them.

Many came with other engines, lets say Enya's Smile as a package and I just set them aside.  I still have scads to clean up, if I start now, maybe by Christmas next year.  Smile

"Let's say Enya's"... Shocked Laughing .. (I'd love to see your collection someday Bob!) .......... another cool little engine that Bob sent in his "care-package" was a Cox buggy engine.



Thumbs Up Thumbs Up Lots of cool parts there! I think that the backplate is fitted with a fine-thread NVA.



I'm not sure about that.. but it looks like one. If it is; it's the only horseshoe-style backplate that I have, that sports one.

Sooner or later.. I'll want to try running a pressure-bladder fuel-feed.. and a fine-threaded NVA would be the ticket. That aside; there's other interesting aspects to this engine. The heat-sink.. and muffler.. the flywheel/fan assembly.. and the I believe it may have a H/D crankshaft. Cool stuff! I'm not sure of the cylinder-porting.. but the CEF "cylinder-identification" archive might give a clue.

The engine is "stuck".. but may only be castor-seized. I'll probably tear it down this weekend to find out more.


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Re: Thanks again rsv1cox "Bob"

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