TEE DEE Having issues

Contrary to a tight shaft to crankcase fit, I had starting problem with a loose shaft fit as the aftermath of the previous owner running the engine with unbalanced prop and excessively wearing the crankcase nose.

You may want to check if there is any sensible radial "play" of the shaft in the case (simply wagging the prop while holding the crankcase firmly), because an excessive radial play will compromise the crankcase seal and lead to fuel drawing, and starting problems

If these are used TD's, the plastic carb bodies are prone to cracking. You can hardly see some cracks but they occur in the threaded area where the venturi screws in. A loose venturi, a cracked carb body or blocked peripheral jets within the venturi will compromise fuel delivery. The TD utilizes a large throat area within the venturi. This in itself can make the engine a bit more difficult to run over a integral tanked Bee.
Some people like myself will drill the venturi out for even more power but the problem occurs when you have a drilled venturi and your trying to run the engine from a tank. I rarely run TD's from tanks, all of mine are run using bladder pressure.

A new TD can also be a bit cantankerous when first trying to start especially with the hi-comp glow head. Decompressing the engine by adding additional head shims can make the engine more docile and easier to start. This may require 3-4 head shims. I'm personally not overly impressed with the needle valves of the TD. These can also suck air causing further fuel delivery problems. I do away with the spring steel ratchet under the venturi . I place a small piece of fuel tubing onto the needle valve which acts as a gasket between the spraybar inlet.

Get the engine to fire up on prime a few times prior to hooking up your fuel line and don't over prime the engine. After you burp it out a few times hook up your fuel line and open your needle about 4 turns. You should be able to place your finger over the venturi totally blocking it and rotate the propeller. The fuel should visibly be seen coming up the line and into the spraybar. Stop choking and prime cylinder and flip.

I have a lot of experience with tee dee and I admit that the tee dee is slightly more difficult to start especially with a silencer my trick for an easy start is do Not prime over by the silencer But rather place a finger on the vetury and turn a few turns until you see the fuel rise in the pipe continue until the fuel enters the engine but do not drown it with fuel I like the .049 with the starter spring a well primed engine feels like this As you turn the propeller with your finger you should feel the compression and the engine giving a small start to ignition this Will offers good resistance sometimes giving a small slow explosion sort of bump on the prop At this precise moment the engine is ready so you give a good swing on the propeller and it should start With the spring starter it's better One thing many do is crank non-stop without even preparing the start with a fuel prime. Or insert too much fuel through the exhaust port which is dangerous and can hydrolock the engine causing possible damage. Too little or too much fuel is harmful and makes starting difficult.

Sorry for the late reply.
Im using Brodak fuel.

I dont think the fuel is the issues.

All my engines are new, great compression. Tried now 5 engines which are now classified as used.

Cannot start TEE DEE engines. Reed valves no issue. Take for instance the 0.074 no issue .

It is annoying . I might just set up to use the Black widow and 0.074 engines. I have 5 of them new. However they are hard to gauge with flooding with the muffler attached so I took it off.

@MANDALAY , did you purchase the problem Tee Dee's from Cox International? Bernie put out a message in:

https://www.coxengineforum.com/t18552-049-tee-dee-needle-valve-bodies-and-049-td-engines-potential-flaw

It is about  a manufacturing defect on his most recent TD production run. If you didn't purchase one of these or other Tee Dees from him, there still is a possibility of a defect in an Estes manufacturing run. I said possibility, because I really don't know.

I'm sure that there is a logical explanation for why there is no fuel feed to your Tee Dees, only running on prime. Also, it is possible that the versions you have, someone modified the venturi opening larger than factory?

They were designed to work under suction feed, but if enlarged, may require a pressurized fuel system (bladder, etc.). Because the suction feed is through a sidewall hole(s) in the venturi throat, the opening is smaller than would be for a spraybar visibly crossing the venturi opening.

Anyway, there are no rocket science issues, and I am sure that once you find the culprit, will be able to get them running, or, get them fixed then run.