Tee Dee carburetor question

I still don't get it.

A carb has a barrel with a hole drilled through it. When the hole is in the vertical position, and one can see down into the carb, this should be full speed.

When the hole is almost closed that should be idle, no? At least that is how all my non-cox carbs work.

That is how nearly all carbs work, your customer must be seeing something wrong.

Carb open=more oxygen=higher RPM.

Carb closed=less oxygen=lower RPM.


If his is different he should write to a scientific institute and report a glitch.

He even sent pictures to demonstrate the problem.

But then, English is not his native tongue either. These are his words:

HELLO BERNIE.- first at all I included tree pictures of tee dee 051( THIMBLE DOME), one show fully open and the engine work well but at idle!! another one almost closed and at this setting it work as full power,. iits work fine and is absolutely operational,. but I wondering it is ok ?? because it works as oposed related to others carburetors and engines,.

Would like to see the pics.

Just thinking out loud:
Could the settings are WAY too rich and it would idle WOT because it's about ready to die from being too rich.

Just running the scenario in my head.... haven't tried it, I do have a carb though.. I could throw it together this evening and try it.. or in the morning.

Does that carb adjust fuel flow or air?

I doubt it though.

Rich=Too much fuel and not enough air so at idle letting in even less air it'd die, when carbed engines are too rich they die at idle.

It could be FAR too lean and there isn't enough fuel being in to keep full throttle going but there would not be a reliable 'idle' at wide open and it would probably die.

If he has set up his engine correctly this is impossible.

All depends on what the carb does, meters air or fuel... I believe.

I think if it meters fuel.. the opposite would occur.

He took the carb apart and then put it back together.

He either has the barrel upside down or teh spraybar rotated the wrong or something else.

It sounds as it the engine runs at full RPM when the carb is almost closed (air / fuel still leaking into the engine somewhere dus to parts mis-installation) and when open it just runs super-rich.

WingingIt74 wrote:All depends on what the carb does, restrict air or fuel... I believe.

I think if it restricts fuel.. the opposite would occur.

Possibly but my understanding was that the tee dee and most if not all 1/2a carbs are air bleed ones and not true butterfly valved carbs like most full size engines use.

I think Bernie is on to something about the spray bar.... that could maybe tend to have an opposite effect.

Cox International wrote:He took the carb apart and then put it back together.

He either has the barrel upside down or teh spraybar rotated the wrong or something else.

It sounds as it the engine runs at full RPM when the carb is almost closed (air / fuel still leaking into the engine somewhere dus to parts mis-installation) and when open it just runs super-rich.

Is it possible for him to return it or to send you some pictures/video of it.

It sounds like if what you just said was the case it's a user error and not your responsibility.

If he has an exploded diagram of the carb and assembled it according to that with everything done up tight enough there should be no such problems.

I could ask for the return and, yes, it is user error. However, we even cover that with our 100% satisfaction guarantee.

Cox International wrote:I could ask for the return and, yes, it is user error. However, we even cover that with our 100% satisfaction guarantee.

That's good, confidence in the products don't see enough of that.

I'll look at my carb when I get home.

Doesn't this carb not work correctly on a TD unless you also install a non-spi cylinder?

How could you get a good idle, say 5k or so, with SPI feeding it more air.

My experience with carbs on the TD's is that you either need to install a muffler or put a non SPI cylinder on it for it to get a good idle.

Is it possible that he is missing the O ring on the needle valve or the carb body is cracked in the back causing an air leak.

first at all I BOUGHT a 051 tee dee, thimble drome-and then received the carb and instaled as is... it start ok ,normaly at half way ,. and when looking for wide open and start to lean it. just two thing happen . first if start to lean its quit or just idling and when closes it just accelerate to full power!! ..finaley testing it I set a mixture wich give a very nice idling at full open and a very very god power at almost closest position. IT WORKS FINE., but a reversed way that it shoud be...is fully operational y that way.- is just strange..I wish to say that I have a super tigre 45.- k&B 18/20/45 and four stroke engines like LASER 120 /150.- I Know how a carburetor works also I'm comercial pilot.- is just strange it all .-

i'm thinking that when you try to lean it out at full open throttle it's not able to draw enough fuel so you have to richen it way up and that slows it down to a nice fat "idle"....then when you close the throttle the restriction now allows it to draw the fuel it needs and the SPI is letting it breath enough fresh air to run at high RPM.

pretty neat if that's really what's going on and if the idle and full RPM are acceptable no reason not to use it like that....you may have just figured out how to throttle the hotter engines without using a restrictive muffler can you post RPM readings?

David

In any event, there is a new carb assembly on the way to you. Let us know if it works better.

hello., today I try mi last chance and remove the muffler of my old QRC babe bee and installed on the tee dee., and.......... WORK GREAT. AND CARB AS IT SHOULD BE!!!! NORMALY!!!! as bigger engines...I dont know the physic effect on the exaust but with the muffler installed in run amazingly well!! and carb exactly as its bigger brothers, the idle fantastic and accelerates terrific!!!
I hope this info be usefull for other users,. is NOT A PROBLEM WITH THE CARBURETOR, but as I note, the combination for the tee dee 051 timble dome , a muffler is required to work properly.- thanks to all for its comments.- juan

Juan,

I am glad to hear that the carb works. It was designed to be used on the TD RC 050, which came with a muffler and a non-SPI cylinder/piston setup. However, non-SPI setup was because of the muffler and not the carb.

The carb should therefore work without a muffler but will work even better if you use a non-SPI setup.

WingingIt74 wrote:All depends on what the carb does, meters air or fuel... I believe.

I think if it meters fuel.. the opposite would occur.

A carby does both of those, hopefully providing the correct fuel/air ratio throughout its range.