RC Carburetor for Cox Pee Wee .020 / .049 / Tee Dee .010 - .020 - .049/.050/.051

Well I'll be, sosam117, that's one I've never seen before, thanks for posting.  

It is an interesting concept for a 3D printed choke tube style carb mount plus carefully machined carb parts for the tank engines, sosam117. About the only thing needed is a suitable engine mounting system. Also, it is an interesting but simple choke tube style carb system for the Tee Dees as well.

It kind of reminds me of the OS Pet choke style carburetors of the late 1950's into the 1960's, that mounted above the venturi intake.



At least for the .049 tank Bees, Bernie's remake of the Ace R/C tank back needle throttle seems to be a simpler and less costly solution, plus makes engine mounting easier. (Just saying,     )

https://coxengines.ca/throttle-for-cox-049-engine-bee-style.html


However, for the Tee Dee's and Pee Wee's, it provides an alternate way of throttling, and an alternate way to upgrade these. The Tarno carbs and Pee Wee exhaust throttle sleeve are harder to come by. I find it interesting that the seller has a late model black striped Top Flite nylon prop of the late 1980's on the Tee Dee .049.

sosam117 wrote:

Interesting find, sosam117, would make a good potential winner for the Cox engine of the month club, particularly for the Pee Wee, IMNSHO.

sosam117 wrote:

Thank you

I would love to have a 010 carb

I would love to have a td 020 carb

2yrs ago I tried to get Greg to mill up some air chokes but to no avail.

I rigged up a venturi to test the concept results:



May 22, 2018
Throttle Add - TD .020

Well done, looks nice.
barrel hole diameter?

Matches the venturi at it's smallest dia.

I wonder if Bernie's reedy throttle could be converted to a TD without too much trouble. Maybe turn the base and chase a thread or something. There is no airbleed of course, so it would be more of a shutoff if you get into trouble. In any case, the carbs would not be too hard to make like the ones sold on feebay.

Wonder how they keep the fuel from leaking out the screws? Only see one oring and the back of the plastic piece is flat so there would be a gap there between the screw and hole in the backplate.

Y want one for tee dee .010 Nice upgrade for m'y litle ford cobra rc car m'y self desing couple carb upgrades tink its posible To place nva on top of valve control air flow and mix at same time???

Looks fairly easy to make the carbs. Especially for $70 US. It would be possible to get a non adjustable airbleed hole on the body of the carb with only a bit of trouble, and a good magnifier. I still wonder if the Cox International reedy carb has a usable stem for a TD? It might pull out of that Surestart style backplate and be threadable? IDK as I don't have one. https://coxengines.ca/throttle-conversion-for-cox-049-engine.html

Are you going to run it? It would be nice to see how it worked.

Hello guys, I leave my opinion about it.
This product is an air valve, it is not a carburetor, that said, using the air valve or carburetor, it will be necessary to pressurize the fuel tank, otherwise the engine at low rpm will not work.
In my opinion and after a few tests, for these engines, with carburetor or valve, an exhaust chamber and pressurizer are needed, otherwise it will not work properly.
If you don't use an exhaust chamber and pressurizer, the best of the best is the throttle ring, which is great for micro motors without pressure in the fuel tank.
Believe me, the answer is always faithful, it will always be there, the acceleration ring is safe, noble and very simple to apply.

In this video, I show a Cox Medallion .049 r / c with acceleration ring, without pressurizing the fuel tank, the response of the engine is immediate, faithful, always responds .... there is no better way to fly safely than with the acceleration wheel!

I have done these tests on Cox .020 and Cox .049 ... it won't work ... it doesn't compare to the throttle ring !!

Cox Pee Wee with acceleration ring! ... incredible!

MauricioB wrote:This product is an air valve, it is not a carburetor, that said, using the air valve or carburetor, it will be necessary to pressurize the fuel tank, otherwise the engine at low rpm will not work. In my opinion and after a few tests, for these engines, with carburetor or valve, an exhaust chamber and pressurizer are needed, otherwise it will not work properly.

The OS Pet .099 used a similar air valve carburetor device, that sleeved into the venturi, effectively reducing the throat diameter at the needle valve assembly. It was used in the earlier R/C's through the mid 1960's. That's how they got around the issue of not requiring a pressure system.



This device does appear to reduce the throat area around the NVA, so it might have sufficient suction to maintain a standard fuel system without pressure. Of course, there would be a loss of wide open throttle HP, but then that would be the sacrifice for a throttle-able engine, but probably more powerful than a reedie anyways. An unmuffled exhaust throttle ring would probably be less restrictive.

I guess that to prove would be to actually test it. These are just my sentiments, not meant to derail any discussion. I only have 1 Tee Dee, the .020, and as such am least qualified to comment.

sosam117 wrote:Then what is the difference between the Cox R/C throttle and the one from Japan -- for Tee Dee engines:

This Japan R/C throttle for a Tee Dee .049/.050


And this Cox R/C throttle for the same Tee Dee .049/.050?


I'm talking about the Tee Dee engines that have front rotor intake and not the rear reed intake.
The group have been talking about the rear intake of a Cox Baby Bee, SureStart, and similar engines.
I am looking at the Tee Dee engines with this R/C throttle.

The carburetor has the fuel inlet regulation needle combined with the air inlet through the venturi at a minimum distance, that is, the venturi opening (air passage) that will suck the fuel flow is integrated and arranged at the same time fuel when venturi is opened. As there is no distance between one point and another, their interaction is immediate and that is why it is called a carburetor, because it efficiently combines the air inlet with the fuel inlet as the venturi opens or closes.
The air valve you have there delivers air to another physical distance from the spray bar, therefore not accurate enough for good throttle response or to keep the engine throttle at low revs, it can of course work but when you accelerate suddenly you won't get an immediate response and in turn when you want to run the engine at low revs the engine will become critical in gear.
If you put this motor (with air valve) in an aerobatic model, you will not have fast acceleration responses, that is, it will not accelerate instantly and the motor may be planted in some flight position.
You can do bench experiences, but then in flight and stunts things change significantly.
For both cases, if you put a carburetor or air valve, it will help a better operation to pressurize the fuel tank, this is for both cases..

GallopingGhostler wrote:

MauricioB wrote:This product is an air valve, it is not a carburetor, that said, using the air valve or carburetor, it will be necessary to pressurize the fuel tank, otherwise the engine at low rpm will not work. In my opinion and after a few tests, for these engines, with carburetor or valve, an exhaust chamber and pressurizer are needed, otherwise it will not work properly.

The OS Pet .099 used a similar air valve carburetor device, that sleeved into the venturi, effectively reducing the throat diameter at the needle valve assembly. It was used in the earlier R/C's through the mid 1960's. That's how they got around the issue of not requiring a pressure system.



This device does appear to reduce the throat area around the NVA, so it might have sufficient suction to maintain a standard fuel system without pressure. Of course, there would be a loss of wide open throttle HP, but then that would be the sacrifice for a throttle-able engine, but probably more powerful than a reedie anyways. An unmuffled exhaust throttle ring would probably be less restrictive.

I guess that to prove would be to actually test it. These are just my sentiments, not meant to derail any discussion. I only have 1 Tee Dee, the .020, and as such am least qualified to comment.

Yes, friend, the reduction in diameter of the venturi in the air valve, is precisely to achieve that the acceleration of air is powerful enough to suck the fuel from the spray bar or spray bar, this is due to the distance between the opening air valve and spray bar. For that reason it falls in turns and in power. It is an adaptation to achieve engine control by sacrificing its power and performance.
The carburetor is efficient because it will do the job of regulating the engine, always maintaining its maximum available power.