.049 Tee Dee Needle Spring?

Donjamin Mon Oct 22, 2012 11:05 am

I just picked up a .049 Tee Dee engine from a garage sale. The engine looks to be in pretty good condition and turns over nicely. I noticed after I put it in my engine test stand that the needle valve is missing its spring. I checked the internet and could not locate a source for a replacement spring. Is there another Cox needle spring that will work as a substitue?

Donjamin
Diamond Bar, CA

SuperDave Mon Oct 22, 2012 11:17 am

Don:

None of my TD .049 and .051's have springs per se but rather a clip that extends out from the needle valve assembly.

Are sure your clip is missing?

fit90 Mon Oct 22, 2012 11:26 am

I like to use a short piece of medium fuel tubing over the needle and needle valve assembly counter part. It holds the needle better than the clip/spring with the added benefit of sealing most possile air leaks.

microflitedude Mon Oct 22, 2012 11:31 am

Sure you don't have a Medallion?

SuperDave Mon Oct 22, 2012 11:57 am

As impied above, the Medallion .049 uses a coil spring on the needle valve which is readilly available from the vendors such as: www.exmodelengines.com

I've never had problem with the clip on my TD .049 & .051's. Seems to secure the needles just fine w/o fuel tubing added.

SuperDave Mon Oct 22, 2012 1:20 pm

Don: So which is it. a Cox TD or Cox Medallion .049?

The Medallion wasn't produced as a "contest engine" the TD was and was built to closer tolerances. The plastic venturi on the TD .049 is black, on a Medallion it is red unless someone has changed them for some reason.

There were also TD's and Medallion's produced by the Cox succssor Estses but that's a different story.

microflitedude Mon Oct 22, 2012 1:32 pm

The Medallion was known as the "Poor man's TD". The porting in the crankshaft and cylinder was mild compared to the TDs. Most think of the Medallion as a more reliable sport engine.

Medallion .049

.049 Tee Dee Needle Spring? Cox_me10

TeeDee .049

.049 Tee Dee Needle Spring? Cox_td10

Donjamin Mon Oct 22, 2012 2:30 pm

I have both the Medallion .049 and the Tee Dee .049. The spring clip is missing from the Tee Dee below the carb body. I tried sourcing the spring clip and it doesn't seem to be available any longer. I noticed that they are still available for the .020 but not the .049. I was wondering if I could substitue the coil spring for the spring clip?

Donjamin

SuperDave Mon Oct 22, 2012 2:37 pm

www.exmodelengines. com has springs that could be sustitued for the clip. 3 for $1.95

**RknRusty** Mon Oct 22, 2012 3:20 pm

Hi Donjamin, welcome to CEF.
Before I ever run a Tee Dee, I do like Fit90 suggested and remove the spring clip and slip a piece of medium fuel tube over the needle and brass boss on the NVA. It grips the needle better and seals it from allowing air past the threads. However, if you PM me your address I'll send you a spring clip.

.049 Tee Dee Needle Spring? SAM_2002

Donjamin Mon Oct 22, 2012 5:49 pm

Very simple solution. Thank you for the post.

Donjamin

Donjamin Mon Oct 29, 2012 10:32 pm

Here is a picture of Tee Dee .049 that I picked up.
.049 Tee Dee Needle Spring? Img-2012

Donjamin

**Cribbs74** Mon Oct 29, 2012 10:39 pm

Hmm,

It has a performance glowhead and a pressure tapped backplate. I am surprised the previous owner didn't go all the way and install a fine thread NVA.

Ron

Donjamin Mon Oct 29, 2012 10:44 pm

Ron,

Being this is my first venture into the Cox Engine Forum, what is an fine thread NVA?

Donjamin

jsesere Mon Oct 29, 2012 11:00 pm

A fine thread NVA has 128 threads per inch and will allow you to fine tune and hold steady RPM's. Here is a picture of one version.
http://www.ebay.com/itm/Kustom-Kraftsmanship-high-performance-needle-valve-for-Cox-Tee-Dee-049-051-/251155823665?pt=Radio_Control_Parts_Accessories&hash=item3a7a0dbc31

**RknRusty** Mon Oct 29, 2012 11:09 pm

Donjamin wrote:Ron,

Being this is my first venture into the Cox Engine Forum, what is an fine thread NVA?

Donjamin

You use a fine thread needle valve assembly when you have a pressurized fuel system. You must have one with a pressure bladder. Or if you run crankcase pressure back to your fuel tank from a pressure tap, I think it makes it a lot easier to needle .

**RknRusty** Mon Oct 29, 2012 11:20 pm

Yours looks like it was tapped, but I don't see the nipple on it. That engine really should get a teardown and cleaning before you try to crank it. That's true of any engine you buy no matter what it looks like on the outside. Clean out the crankcase and crankshaft bearing journals. And clean out the NVA and the 3 sprinkler holes in the venturi. I remove the needle and use brake parts cleaner to blast out the NV orifices and de-gunk the engine. With safety glasses of course. Everyone here has their favorite methods. Does that cylinder have a "4" stamped on it? .049 Tee Dee Needle Spring? Img-2012

Donjamin Tue Oct 30, 2012 11:06 am

Rusty, I agree with you on the idea of cleaning the engine before firing it up. This one sat for quite a while, but turns over nicely by hand. Fortunately the piston and cylinder wall aren't rusted or scorched. I'll check this evening and see if the cylinder has a number 4 marked on it. What is the meaning behind a number 4 on the cylinder?

Donjamin

SuperDave Tue Oct 30, 2012 11:40 am

Donjamin:

This site has a wealth of information about cylinders and their numbers. Keep this for reference because it is very specic and it would be very difficult to remember upon one reading.

Cox model engine - Wikipedia, the free encyclopedia

**RknRusty** Tue Oct 30, 2012 11:41 am

The #4 designates the Tee Dee .049 cylinder. Just something to check to verify what you have. You can also look at the internal bypass porting to confirm it too. Until Cox's latest days, they had different porting than any other cylinders.

I'll find a picture later and post it.

Donjamin Tue Oct 30, 2012 11:09 pm

Took a look this evening and there is a number 4 imprinted on the base of the cylinder wall.

.049 Tee Dee Needle Spring? Img_0610

Donjamin

**RknRusty** Tue Oct 30, 2012 11:27 pm

Excellent.

JPvelo Wed Oct 31, 2012 12:06 am

I picked up a tee dee today that had a spring as opposed to a clip. Older model and of course no way to know if it came that way from the factory.
Jim

Mark Boesen Wed Oct 31, 2012 9:49 am

It's pretty safe to say it never came from the factory with a coil spring, all Tee Dees have always used a flat clip to hold needle.

SuperDave Wed Oct 31, 2012 10:21 am

JP:

Could it be that at some point the NVA was changed to a fine thread version?

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