Tee Dee .09 rebuild.. and run!

1/2A Nut wrote:You can run it up with a elect starter to warm up the head naturally with a bit of after run oil thru the
intake, this will allow you to remove the old glow head. I have used this trick with consistant success
over the years.  

My homemade elec. starter wouldn't crank this engine. I tried that when I was having trouble starting it before. It works fine on my Bee engines.. but the .09's compression was too much for it. (maybe that's a good sign..)

I have a heat-gun which should do the trick. I've loosened the cylinder from the case.. so I'll try heating the cylinder apart from the engine to remove the head.

I also haven't removed the venturi to check the spray-bars' 3-hole flow yet.

I just downloaded the Tee Dee .049/.051/.09 instruction sheet from the forum archives. I need to better familiarize myself with the Tee Dee engine-parts before I take the whole engine apart.

The black wrench I sent has cutouts that fit the venturi. There are only a handful of parts in that engine. It's super simple and those wrenches have everything you need to disassemble and assemble.

Cribbs74 wrote:The black wrench I sent has cutouts that fit the venturi. There are only a handful of parts in that engine. It's super simple and those wrenches have everything you need to disassemble and assemble.

Getting there..



I still need to remove the drive-plate. IIRC I can install a stub-screw with hub-nut and press the crank out through the rear of the case using a bench-vise?

I have a Dr.'s appointment at 1:00 so I'll stop for now and check-back here before proceeding.

There are two easier ways, but a little more invasive. Both safe if done properly.

Put the case on a hard surface, nose pointing up, backplate off. Screw prop screw into crank all the way. Give the screw head a couple firm taps with a small hammer. Drive plate should pop off. This is what I do

Second way is easier, but make me cringe. Unscrew the carb body collar until the drive plate pops off.

There is no need to take the front end appart, unless you have a leak there?

I fired up a .09 medallion today, I have mounted one of the aftermarket RC exhaust on it but haven't really tried it yet. So a make-shift engine stand and it fired right up. They are loud though so I didn't run it much, will need to go to the field in order to do that.

With an exhaust prime it would fire every time. A short screaming burst of power in true Cox fashion.
It was actually a little tricky to get the prime-run to last long enough inorder to draw fuel, so the needle had to be opened up quite a lot and then closed again once it was running off the tank. Priming in the intake didn't achieve much, it might just leak out through the front end...?

I also tried a Queen Bee head, thinking it might work well with the throttle. But it had too much compression (on one head shim) and the engine would only rock back and forth. I never had much luck on the Queen Bee with that head either, but never thought about lowering the compression at the time, that is perhaps worth a revisit...

Cribbs74 wrote:There are two easier ways, but a little more invasive. Both safe if done properly.

Put the case on a hard surface, nose pointing up, backplate off. Screw prop screw into crank all the way. Give the screw head a couple firm taps with a small hammer. Drive plate should pop off. This is what I do

Second way is easier, but make me cringe. Unscrew the carb body collar until the drive plate pops off.

yea... I started to unscrew the collar earlier when I realized that it was starting to bear-on the drive-plate. Apparently I could have kept going.. I didn't know.. and thought "oh crap.. I'm gonna' break something".

Thanks for the tips Ron. I feel a little more comfortable now.. knowing that I had the right idea on my question of how to proceed.

I actually wasn't expecting the venturi to screw out of the carb along with the NVA I thought the needle-valve "body" was theaded to accept the venturi. This makes more sense now. I had originally thought that the "spraybar" had three holes.. That's kind of stupid thinking on my part.. ehh?

Surfer_kris wrote:There is no need to take the front end appart, unless you have a leak there?

I fired up a .09 medallion today, I have mounted one of the aftermarket RC exhaust on it but haven't really tried it yet. So a make-shift engine stand and it fired right up. They are loud though so I didn't run it much, will need to go to the field in order to do that.

With an exhaust prime it would fire every time. A short screaming burst of power in true Cox fashion.
It was actually a little tricky to get the prime-run to last long enough inorder to draw fuel, so the needle had to be opened up quite a lot and then closed again once it was running off the tank. Priming in the intake didn't achieve much, it might just leak out through the front end...?

I also tried a Queen Bee head, thinking it might work well with the throttle. But it had too much compression (on one head shim) and the engine would only rock back and forth. I never had much luck on the Queen Bee with that head either, but never thought about lowering the compression at the time, that is perhaps worth a revisit...

I don't know if I should take the front-end apart Kris.. but it has been suggested as a measure of inspection. The threads inside the carb are pretty gummed-up. Maybe there's some de-varnishing that could be done to improve the overall performance? I won't know unless I take it apart. The crank has no side-play.. so I don't think I'd be compromising any sealing by cleaning it up.

I have some more questions.. but have another appointment for PT at 5:00.. so I gotta' run.

I would simply leave the front end alone, unless the plastic has cracked or something, there is nothing really to look at there....
(just check that the timed pressure line is not drilled out)

If it has good compression and a good glow plug, it should fire off on a piston prime. After that comes the fuel draw, and that's about it.

Surfer_kris wrote:I would simply leave the front end alone, unless the plastic has cracked or something, there is nothing really to look at there....
(just check that the timed pressure line is not drilled out)

If it has good compression and a good glow plug, it should fire off on a piston prime. After that comes the fuel draw, and that's about it.

.....and if it's too freakin noisy(which it will be), let me know. I have a cox muffler
that'll help, but only a little. You'll only need plugs, instead of plugs and muffs.
Also, the QueenBee muffler will fit too.
Then again, neither may fit the the thin wall cylinder.
Bob

Kris, is this photo of the Queen Bee glow-head?



You mentioned trying it on your .09 Medallion...   Am I to understand that the .074 (Queen Bee) head will fit the Cox .09 cylinders? If my engine turns out to be a good runner.. I'll want to know what my options are for sourcing replacement-heads. Not that the Queen Bee head will be easier to find.. but it is a high-compression head.. and probably a better choice than a conversion-head. It looks to have much less combustion-area (higher compression) than a Tee Dee head. I know even less about the .074 Queen Bee than I do the Tee Dees..

I checked the pressure-tap on my Tee Dee .09 and it has not been drilled out.

dckrsn wrote:

Surfer_kris wrote:I would simply leave the front end alone, unless the plastic has cracked or something, there is nothing really to look at there....
(just check that the timed pressure line is not drilled out)

If it has good compression and a good glow plug, it should fire off on a piston prime. After that comes the fuel draw, and that's about it.

.....and if it's too freakin noisy(which it will be), let me know. I have a cox muffler
that'll help, but only a little. You'll only need plugs, instead of plugs and muffs.
Also, the QueenBee muffler will fit too.
Bob

Wow... is it really that loud? This made me curious if my homemade .049 muffler would fit the .09 cylinder.. and guess what?...




It does! Granted.. the cylinder must be removed to install it, unlike the .049's.. but the cylinder has to be removed to install the "Cox" muffler anyway. I had wondered previously whether my muffler would fit.. and there's actually more room for it between the cylinder and carb, than there is on a Tee Dee .049/.051.

 Cool, that's gotta be better than the Cox one.
Oh, and the .09 is louder than my Sportsman.
Bob

dckrsn wrote:  Cool, that's gotta be better than the Cox one.
Oh, and the .09 is louder than my Sportsman.
Bob

Well.. I don't know that it's better Bob.. but it does fit. Let me know if you'd like to try one.. and I'd be more than happy to put a muffler-kit together for you.

roddie wrote: Am I to understand that the .074 (Queen Bee) head will fit the Cox .09 cylinders?

Yes, it is a direct drop-in. The same head is also used on the TD .09RC.

Here is a little comparison of the few heads that are/were available (things were a lot easier to source some ten years ago). From left to right we have the stock head, the Queen Bee/TD RC and the last one is a Turbo plug head (made by Ron Valentine). I have always been very sceptical towards using regular plug on the .049, but on a .09 it might work. On the Queen Bee I used mostly the Turbo head, since then one can also play with the heat range of the plug.

Hey Kris and others, have you tried a Queen Bee with a Medallion head? I have a beat-up Queen Bee with mangled head fins and a damaged muffler. I came across a couple of Medallion .09 heads and an .09 muffler kit, I tried both of them on the QB and it looks pretty good. Compression with the Medallion head "feels" OK, but then again the original head or the plug may have been loose when I tried it.

Anyway, with the .09 parts the Queen Bee looked pretty good. Its carb is shot too, so I am thinking about making a new adapter or a backplate so that I could install a .049 Tee Dee venturi and needle valve assembly directly on the back of the crankcase. It should not be very difficult to make as the Queen Bee has the separate aluminium reed valve assembly. I just don't have a suitable tap to make the thread for the venturi. I forget what the size is, but the thread is the same as on standard glowplugs. I already have a name for the hybrid, I call it "Queen Dee"

Coxinternational has several of the plastic parts for the Queen Bee carb, or even the whole carb if you need it. I think that would be the easiest, and the engine is not very powerful for its weight (to be modest), so the only good thing it offers is the throttling ability. You do need to add an air-bleed hole for the carb, and it will work better.

I don't have any notes for the Queen Bee with a TD/medallion head, only with the turbo head;

Graupner 6x3 prop: 17400rpm  (it might be a little better than that, but that's what I have in my notes)
Graupner 6x4 prop: 15800rpm (the engine was heating up a bit on this prop though, dropping from initial+16000rpm )

So powerwise it is like a good .049 engine, but it has twice the weight. It is only when I converted it to a Diesel that it started to be really useful.

I have a short video of it on glow, with the graupner 6x3 prop (it seems to briefly run a little stronger than my notes says there... );

KariFS wrote:Hey Kris and others, have you tried a Queen Bee with a Medallion head? I have a beat-up Queen Bee with mangled head fins and a damaged muffler. I came across a couple of Medallion .09 heads and an .09 muffler kit, I tried both of them on the QB and it looks pretty good. Compression with the Medallion head "feels" OK, but then again the original head or the plug may have been loose when I tried it.

Anyway, with the .09 parts the Queen Bee looked pretty good. Its carb is shot too, so I am thinking about making a new adapter or a backplate so that I could install a .049 Tee Dee venturi and needle valve assembly directly on the back of the crankcase. It should not be very difficult to make as the Queen Bee has the separate aluminium reed valve assembly. I just don't have a suitable tap to make the thread for the venturi. I forget what the size is, but the thread is the same as on standard glowplugs. I already have a name for the hybrid, I call it "Queen Dee"

Hi Kari, The thread size for a standard glow-plug is 1/4"-32. I had that tap.. but haven't been able to find it. I bought it to make conversion-heads from standard Cox glow-heads to use standard glow-plugs. They were crude though.. and I never got the chance to do much experimenting before misplacing the tap. The plugs I had at the time were "short" plugs.. but had a large cavity surrounding the coil which lowered the compression of the head. I notice that the "turbo-head" that Kris shows in his comparison-pic (far right) has a plug with a much smaller cavity than the other two.



I'm sure that this must make a difference.. along with the depth/shape of the combustion-chamber that Valentine machined for it.

Did Cox sell a replacement "plug" for their .074/.09-RC head?  If not.. they must have recommended a certain type be used?

I wonder "if"... using a Tee Dee glow-head (h/c) to make an "adapter-head" would work better on a non-Tee Dee engine? Let's say a Medallion .049/.09/.15 or a Bee engine? Depending on the plug used (smaller coil-cavity/short plug) it would offer higher-compression; comparable or possibly more than the standard Cox head. I realize that it's a more expensive head to do a conversion on.. and the commercially-available ones weren't made from h/c heads.. at least the one's that I've seen aren't.

I originally thought that power-flushing the NVA through the nipple with needle wide-open would have cleaned-out the venturi. I was wrong about that. I couldn't blow air through it while holding a finger over the other end. I took a piece of .015" music-wire and ran it through each of the three holes to find congealed fuel in all of them with two completely blocked.



I guess I wasn't experiencing any flooding from the tank at least. I then took a short piece of Dubro small (1/2A size) silicone fuel-line and twisted one end into the spout of a rubbing-alcohol bottle.. and the other into the bottom of the venturi. They were about the same size orifice which held the silicone tubing tight.



Using a large bowl and with my finger sealing the top of the venturi, I inverted the bottle of rubbing-alcohol and applied pressure. At first just some "trickling".. then suddenly all three holes cleared, emitting an equally-even stream. One less thing to wonder about.

Good point, Roddie, I use brake cleaning spray, connecting its sprayer with a silicon tube to the bottom spout of the venturi, and by sealing the intake side with my finger, pressure-flush the 3 orifices.

TD-s are easy to diagnose with orifice clogging problems if they run weakly and do not seem to want to react to needle valve adjustment. When I notice that - although rather seldom, because I  use, as a rule,  filter in the fuel line - I immediately remove and clean the venturi including the 3 orifices, and blow through the anodized spray-ring too to make sure its single orifice is also clog-free.

That's a big one.
Way ta go Roddie.
Bob

roddie wrote:
Did Cox sell a replacement "plug" for their .074/.09-RC head?  If not.. they must have recommended a certain type be used?

Yes, there is/was a specific plug for these, but it looks like most regular plugs. Bernie is also selling them.

If you want a higher compression ratio it is quite easy to just remove a little bit of material in a lathe. I think the compression ratio itself is more important than the very head shape. The head shape is more for the final tuning in competition engines. The high compression head for the .09TD is a trumpet shape all the way to the sealing surface (it doesn't have the step or squish band that the other high compression heads have).

On the .020TD I have seen a big improvement by removing about 1-2 heads shim worth of material from the sealing surface. One has to remove a little bit from the lowest cooling fin too. I can then run with one head gasket and get a very nice and clean 2-stroking sound on only 10% nitro.

Here is the "shaved" .020 head, I think I've already posted it somewhere else on this forum;

roddie wrote:I originally thought that power-flushing the NVA through the nipple with needle wide-open would have cleaned-out the venturi. I was wrong about that. I couldn't blow air through it while holding a finger over the other end. I took a piece of .015" music-wire and ran it through each of the three holes to find congealed fuel in all of them with two completely blocked.



I guess I wasn't experiencing any flooding from the tank at least. I then took a short piece of Dubro small (1/2A size) silicone fuel-line and twisted one end into the spout of a rubbing-alcohol bottle.. and the other into the bottom of the venturi. They were about the same size orifice which held the silicone tubing tight.



Using a large bowl and with my finger sealing the top of the venturi, I inverted the bottle of rubbing-alcohol and applied pressure. At first just some "trickling".. then suddenly all three holes cleared, emitting an equally-even stream. One less thing to wonder about.

Hi Roddie, about cleaning the three holes is what I meant from the beginning!
Yes now!

MauricioB wrote:
Hi Roddie, about cleaning the three holes is what I meant from the beginning!
Yes now!

Thank You Mauricio! I still have a lot to learn my friend!