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

MauricioB wrote:

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..

aspeed wrote:

MauricioB wrote:

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..

I think the main difference between the two carbs is the fact that the Cox one has an adjustable air bleed which will control the mixture at idle somewhat.  The Japanese one as well as the reedy Cox one is really just a choke which will throttle down a bit but then be too rich at idle.  I am sure an air bleed in the Japanese one or even the reedy Cox one would give a serviceable carb.  It would not need to idle down to 3,000 rpm for the plane to fall out of the air.  As far as the position of the needle opening to the air valve, I doubt the 1/8" difference in position would make any difference in running.  Just look at the remote needles in most of the larger motors that work quite well in most cases.  Of course the air bleed hole in the Japanese or reedy carb would need to be tried on a plane and tested thoroughly to make any real conclusions.

aspeed wrote:Either way the fuel and air is mixed between the top of the opening in the rotating barrel and the opening window in the crank for atomization. I don't think 1/8" up or down in that area would make a lot if difference in running.  I have seen control line conversion carbs with the fuel inserted much above the optimal position, slightly below the smallest diameter where it is necked down.  They all seem to work just as well either way.  Any comments and improvements are always encouraged.  I always want to know more.  (and maybe go faster) I believe the atomization is only really going to happen, or really be important right at the exhaust port in the cylinder.  I have used venturis with spigots, and holes in the side and spray bars all the way through with no differences in power, given the air opening size being the same.