Fit of TD 09 R/C Muffler

That sounds like a good idea keep the airplane cowl clean but that doesn't explain the 1/32" slop. The black "washer" on the top is perfectly flat. Apparently there are just two parts, normally, the aluminum muffler and the black "washer", or "disk with a hole in it", then.
Jim

RudderOnlyPlot wrote:I have a question about the fit of the muffler on my TD 09 R/C. I have one that I have not used in ages and I had converted to a standard TD 09, having removed the throttle and muffler and installed the standard fixed needle valve assembly. Well, today I re-installed the throttle and the muffler and found that the muffler was loose, moving up and down on  the cylinder about 1/32"! I could not see any reason why it would do that unless I am missing a part, a spacer, or something. There was just the aluminum muffler and the thin black "washer" that goes on the top. To fix it I turned a .040" thick, 0.75" ID and 0.85" OD aluminum washer on my lathe and put it between the crankcase and the muffler. It works great but I don't understand why it did not fit right in the first place when I don't remember any issue like hat before I put it in the drawer many moons ago.

Jim, welcome to the forum! I am a rudder only lover, too! Got my start on R/O back in 1972, when I bought a Christmas gift for myself at a Virginia Beach hobby store, the then novel Ace R/C Pulse Commander proportion on 26.995 MHz (Brown freq.) and Adams Baby Twin magnetic actuator ($70 plus tax). I had a blast with it and my 27" Top Flite R/C Schoolboy powered by a .020 Pee Wee engine. It taught me how to fly R/C.

There is a spacer supplied with the mufflers. If the engine did not have a snap starter spring on it that circumferenced the bottom exterior of the cylinder for locking the end of the spring down, the spacer was used to fill the gap. It is possible that it could have been misplaced (thin, easily missed) or if your engine came with a snap starter and you not reinstalled it, this may explain the slop.

Your manufacturing a spacer mainly created a replacement part for the missing.

Drawing of the engine and link to instruction sheet

https://60d46b49-a-62cb3a1a-s-sites.googlegroups.com/site/coxengineid/Cox%20TD%20RC%2009.pdf?attachauth=ANoY7crzMyaCan7weS_BR9v0F8sCB9mbbmtkxsYyGivgd-2ArJk16Xtz4JwXOz_GUZrIH-6jmyp37o7uARujfAtz-96-G9WB70fhf0dppxJCK4yvodUbtpNnYLaK9r9mufa2AdlBtqSH_X6WF0QacrSgFzPxvTJdSXOLvpepCsLTek9PD0YZuUlWXVPVc7IkFPecXkqiZ5pDj1-FWWjBU8NJlUS3dhO-Lg%3D%3D&attredirects=0

My bad on models. I was thinking someone modified it by adding an exhaust throttle muffler, which as a kit does come with a spacer ring to fill in place of no starter spring installed.

The only Tee Dee I have is a .020 one. It does make sense that the later 1990's Tee Dee R/C had SPI removed and cylinder reported to increase power without SPI under muffled conditions.

The .09 Medallion had SPI and exhaust throttle muffler. It reduced performance due to exhaust gases recirculating from SPI diluting the incoming fuel charge. But, I guess that is the compromises they felt were acceptable to have a lightweight throttleable engine.


My Medallion .09 R/C with exhaust throttle muffler

The Medallion .09 R/C would benefit from a latest Tee Dee cylinder and piston without SPI. But, those nowadays are as common as hen's teeth.

GallopingGhostler wrote:

RudderOnlyPlot wrote:I have a question about the fit of the muffler on my TD 09 R/C. I have one that I have not used in ages and I had converted to a standard TD 09, having removed the throttle and muffler and installed the standard fixed needle valve assembly. Well, today I re-installed the throttle and the muffler and found that the muffler was loose, moving up and down on  the cylinder about 1/32"! I could not see any reason why it would do that unless I am missing a part, a spacer, or something. There was just the aluminum muffler and the thin black "washer" that goes on the top. To fix it I turned a .040" thick, 0.75" ID and 0.85" OD aluminum washer on my lathe and put it between the crankcase and the muffler. It works great but I don't understand why it did not fit right in the first place when I don't remember any issue like hat before I put it in the drawer many moons ago.

Jim, welcome to the forum! I am a rudder only lover, too! Got my start on R/O back in 1972, when I bought a Christmas gift for myself at a Virginia Beach hobby store, the then novel Ace R/C Pulse Commander proportion on 26.995 MHz (Brown freq.) and Adams Baby Twin magnetic actuator ($70 plus tax). I had a blast with it and my 27" Top Flite R/C Schoolboy powered by a .020 Pee Wee engine. It taught me how to fly R/C.

There is a spacer supplied with the mufflers. If the engine did not have a snap starter spring on it that circumferenced the bottom exterior of the cylinder for locking the end of the spring down, the spacer was used to fill the gap. It is possible that it could have been misplaced (thin, easily missed) or if your engine came with a snap starter and you not reinstalled it, this may explain the slop.

Your manufacturing a spacer mainly created a replacement part for the missing.

Hi "GallopingGhostler",

Well, that's pretty interesting! I don't know if that's the answer in my case, but it's definitely good to know that there is something such as a spacer. I measured the height of the muffler attachment portion (the part that goes around the cylinder) and got about 0.57 inches while the height of the cheaper round muffler (part number 2640) with the adjustable opening is 0.62 inches, 0.50 inches different, and these are supposed to fit on the same engine??

Cool about your Rudder Only interest. I got my start around 1961 with a Minnie Mambo, Citizen-Ship LT3 super-regen relay-less receiver, and a self neutralizing rubber powered escapement. I entered the 1963 Nationals in California flying a .19 size "Over the Rainbow", Mighty Midget powered proportional rudder with quick blip three position motor control. I won fourth in the Junior Single Channel category. Of course, there were only six entrants. :-) My two brothers, a friend, and I drove all the way across the US in my dad's 1962 Chevy station wagon to get there.

I think the spacer thst George refers to was available for the 049 mufflers only? At least I gave not seen a spacer for the 09, but it does not mean there is no spacer.

The height difference of the 2 mufflers is bridged by the different vertical buckling of the black central rings. The ring diameter on the cheaper muffler is larger and with the same angle of buckling the vertical sinking of the ring center is more than with the more expensive RC muffler whose central ring has smaller diameter.

I figured it out, with the help of you who chimed in with your two cents, which confirmed how it should be! As it turned out, I once had two TD 09s with the standard needle valve (no adjustable carburetor). One was that way from the start and one was the one I had converted from the RC version. Well, I sold one of them on eBay and I sold the wrong one! I sold the one that was converted, not the one that was always a standard TD 09. So I've actually been doing now is trying to convert an original standard non-RC version to the RC version and the cylinders are different! Luckily I had a used RC version cylinder in my drawer to look at and measure! The RC version has a thicker ring at the bottom of the fins to support the muffler and the standard one doesn't. So the muffler was being held on place by the lowest fin, which is higher than the ring on the RC version cylinder.
Jim

Jim,

The RC cylinder with the muffler is probably a non-SPI, while the normal cylinder is SPI..as far as I know they only differ in the exhaust port bottom level, but the lowest fin is at the same height? At least I am using the RC muffler on the normal cylinder with SPI, and the muffler fits snugly.

I'm not familiar with the term SPI. What does that stand for?
Jim

SPI= Sub Piston Induction...the piston skirt bottom clears the exhaust port when on top dead center, thus the depression in the crankcase will inhale a little more air, which will allow more fuel to be burnt, thus increasing the engine output. (In fact you can open the needle valve more to allow the additional fuel in, without making the mixture too rich.) If a muffler is used on SPI engines, then it is exhaust gas and not fresh air that is inhaled under the piston skirt, and this reduces the engine output. So stock engines with muffler were always non-SPI...

You can check if your engine is SPI design or not, by cranking the piston to the top dead center and see if there is a small gap opening between the piston skirt, and the exhaust port bottom.

I got a bit curious, so I've checked on two of my engines. There are at least three obvious differences in the cylinders, and the RC version has:
- thicker cooling fin that sits against the muffler
- narrower exhaust opening (the lower part is higher in order to not have SPI)
- additional transfer channels (one "boost" port on each of the two main ones), this creates a swirl that supposedly improves power.

Here is a comparison:

Thanks, I have only straight (non-RC) 09-s, I have never seen this difference.

Thanks, "Balogh"! I now know three times as much as I knew before! . Anyway, my problem is solved. I've reassembled an RC version using the right cylinder and Bob's your Uncle!
Jim

balogh wrote:I think the spacer thst George refers to was available for the 049 mufflers only? At least I gave not seen a spacer for the 09, but it does not mean there is no spacer.

The height difference of the 2 mufflers is bridged by the different vertical buckling of the black central rings. The ring diameter on the cheaper muffler is larger and with the same angle of buckling the vertical sinking of the ring center is more than with the more expensive RC muffler whose central ring has smaller diameter.

balogh, one thing I appreciate about CEF is that each one of us has a certain perspective based upon our experiences, backgrounds, mental intuition, and etc. Not all of us has total expertise except for a limited few, and I certainly don't have it all scoped out. (Sorry, I don't have a need for speed and as such am weak in that area. I like torque - bigger props. ) Some have very good experience in a particular area. Thanks for your inputs and intuition.

There was a set of instructions that came with the mufflers, I think it was one sheet for the entire series of sizes, thus, as from my memory, (which as time passes, gets dimmer unless renewed), had additional parts to accommodate as many situations as possible for a successful fit, due to the variations in cylinders and crankcases.

But, nonetheless, I am glad that RudderOnlyPlot got his situation sorted out. Also, I am finding it interesting that apparently there are some less documented cases of variations within a series, and with things being sold on the Internet, find some limited editions that didn't quite fit the mold of the commonly massed produced, or were initial runs quickly modified to make the rest of the series more successful.

I think that whatever we do, we have fun doing it, because life is short, and whatever we do, when we pass, our so-called prized possessions are not as treasured by most of our decedents, so they become bulk estate sales items.

Thus, whatever we do, we support each other, share successes with each other, we rejoice with each other, when we are wrong, correct each other, we are community.
That is why we are here. So, all comments and corrections are appreciated.  

Thanks Greorge I hope no harm was taken, I was simply unsure if the 09 also had that ring. I know 049 mufflers had .looks like COX compensated that height difference by the permanent, thicker bottom fin on the 09 as Kris discovered,so maybe the ring on 09-s was not needed.

This is an instruction sheet for the 049-s. The spacer was needed on engines without a starter spring. (Refer to pint 3).

As 09-s had no starter springs at all, I guess the spacer ring is for 049-s?

No problems, balogh.

I bought the same muffler with silicon cover from Bernie several years ago, I guess yours came from the same lot? The same came stock on my R/C Bee. I don't know if true, but heard something to the effect that Cox was involved with a copyright lawsuit over the silicon cover, seems someone else had already patented the use thereof, although for larger engines. (Lawsuits and current corporation abuse toward individuals - artists and inventors, another topic for the redneck zone   ). I think this also contributed to the short life of the R/C Bee, and why we do not see these mufflers on other engines.

The nice thing about the silicon covered muffler is one can easily remove the silicon cover and use it as a regular throttling ring if noise reduction is not required. This is especially beneficial for engines with SPI, so they can function properly without exhaust recirculating, diluting the fuel-air charge. Most of the time, I flew my Minnie Mambo without the silicon cover. This you can't easily do with a metal throttle muffler.

Those not needing muffling, I have always loved the exhaust throttle rings. They are one of the easiest ways to throttle a Cox .049, flew my Airtronics 36" Q-Tee with one back in the late 1970's on a Golden Bee, very effective, does not interfere with SPI. I had an earlier Medallion .09 R/C with such I had bought in the 1970's, but when for a short decided to out myself from the hobby, gave it to my brother. Now I wished I kept it.

-- György

It is possible to eliminate the SPI I often do this , take my last little project as an example use a tuned rc pipe   its exaust collector chim the cylinder To cancel spi i use a no 4 cylinder basic jerobee rc .049 tee dee .To compensate the lost of compression i use a modified head convertion
Note the glow plug on pic is just a dust cover during  build If done right the loss of power is minimal Or even nothing lost