Medallion Cylinders

Darren19 Fri May 10, 2013 6:52 pm

Thanks much on the clarification on the .049 as opposed to the .051 piston and cylinder swap. The picture too were very much appreciated!
I also haveb a Cox .049 Medallion. I notice seeing cylinder being sold with piston togeth forman .049 Medalion. Are these piston/cylinders for the Medalion specific? I mean can a TeeDee .049 fit on the .049 Medalion or is the Medalion cylinder a different animal all together?
Thanks!!
Darren

SuperDave Fri May 10, 2013 7:18 pm

Darren:

The TD .049 is billed as a "competition" engine and, although very similar to the Medallion it not built with as much attention to detail like cylinder porting.

Some will moan but the Medallion is sometimes called "The Poor Man's TD". Watch the howls to follow. lol!

SD

**RknRusty** Fri May 10, 2013 7:19 pm

Yes, the piston/cylinders are interchangeable. People even put Tee Dee P/C sets on Bees too. The Medallion Cylinder is fairly tame in it's porting compared to the high flow porting of the Tee Dee. So putting a TD cylinder on a Medallion would seriously hop it up. Going the other way would suck the life out of a Tee Dee. The only Medallion I own has a new style SPI piston/Cylinder set with the double slit exhaust ports. It's a much stronger runner than in it's original form. The Medallion .049 originally had a #2 cylinder with a single bypass port inside. The Tee Dee .049 has a #4 stamped on its cylinder, and if you look at its internal porting it's different from any other Cox. Many Bees had #2s before the Medallion. But you can swap them all around freely. I think the TD .051 has a #5 on it.

Darren19 Fri May 10, 2013 7:22 pm

Great answer Rusty all clear. Thanks very much!
Darren

SuperDave Fri May 10, 2013 7:25 pm

Let's not fail to mention the the TD carries a high-compression cylinder head too IF it's "correct".

Darren19 Fri May 10, 2013 7:27 pm

That is true too Dave. I have heard the high compression head adds 6-800 rpm over the standard head. Is that accurate or is theere any more updates on those stats?
Darren

**Cribbs74** Fri May 10, 2013 7:28 pm

A Medallion can be likened to good running Black Widow. At least in my experience anyway. The plus is it's beam mount so you don't have to deal with the tank leaking issues.

Ron

**RknRusty** Fri May 10, 2013 7:34 pm

Darren19 wrote:That is true too Dave. I have heard the high compression head adds 6-800 rpm over the standard head. Is that accurate or is theere any more updates on those stats?
Darren

That's pretty conservative. It all depends on the engine type, and individual finicky ways of each. But more than 1 or 2K RPM, or even more increase is possible with the right prop and fuel.

Darren19 Fri May 10, 2013 7:34 pm

Good analagy Ron. Benefits noted. The only difference I am aware between the BW and the Medallion is the Medallion has about 2-5000 more rpm right? If all is working correctly right? Or is this not accurate?
Darren

**Cribbs74** Fri May 10, 2013 7:42 pm

Darren19 wrote:Good analagy Ron. Benefits noted. The only difference I am aware between the BW and the Medallion is the Medallion has about 2-5000 more rpm right? If all is working correctly right? Or is this not accurate?
Darren

Darren,

It really just depends on a lot of variables. I can make a BW turn close to same RPM as a TD with very little effort if I wanted to. In box stock form and on paper the Medallion is a quicker engine. In the air is where the rubber hits the road and the medallion and the widow seem about the same to me in that regard.

Ron

SuperDave Fri May 10, 2013 8:14 pm

Darren:

I mention the high-compression head on the TD because many I've seen used and for sale have the correct head head swapped for an inncorrect standard Cox glo-head.

High-comp heads come in either original style with "knurling" or current production with out the "knurlling".

Personally I like the original style and only recently bought two from one of our vendors/

SD

Darren19 Sat May 11, 2013 1:16 am

Ron you say you can make a BW turn the same rpm as medallion .049 with little mods. Do you mind me asking what those mods might entail? I too have a BW that I wouldn't mind spinning at 22000.
Thanks!!
Darren

**RknRusty** Sat May 11, 2013 3:56 am

This PDF article is a good start:
https://dbabd7f0-a-62cb3a1a-s-sites.googlegroups.com/site/nitroengine/TheRevised2011GibeaultMouseRaceProgramv3.pdf?attachauth=ANoY7cpSdoWT9VWZFJV9LAkWRqLU-NbfoCXIGVhLniiyy4Zt_MRI4o4mnzWXgwFmcgvVuB7sRG2Z43WjGHbMNzUBRBJdwHrCLnfJFwk_AnbH_uUbeyBfpo_1Yl2KuATYTdbBPIUI5oyt2VFnrnfAKPTw3kO0He7phLuNJ_WBBkxTKoYM1SCdxLKNumeUehJ3ByuIdn_2au1dhHYsLYkViJRCNTTQgv4TWmD1MruZ_70gdalYwcNJfqRtp4LJL6S-qSy1zf3H4ah4&attredirects=0

Darren19 Sat May 11, 2013 5:07 am

Thanks got it. Some good ideas thanks!

**Cribbs74** Sat May 11, 2013 7:09 am

Darren19 wrote:Thanks got it. Some good ideas thanks!

Yep, that is where I would have sent you. Thanks Rusty.

fredvon4 Sat May 11, 2013 9:32 am

The biggest difference in the TD vs Medallion is the crank shaft and carb body

In my opinion the original style high compression glow head is very good but a tad pricey these days...the Merlin drop in plug and clamp are a better value and in my experience RPM and power is comparable. The Nelson plug can wake the engine up some and also a very good value over the current cost of true TD HC glow plug heads

SuperDave Sat May 11, 2013 12:10 pm

Fred:

I like the appearance of the OEM TD .049-.051 Cox glo-head and recently purchase of pair of them from Bernie @12.50 each. Call it a matter of personal preference.

One was used to replace an incorrect head on a .051 and the other is simply a spare. It seems in all my years in modeling I've had maybe five glo's ever go bad.

SD

fredvon4 Mon May 13, 2013 8:00 am

SD agreed on the aesthetics...Wow! Having only 4 or 5 glow plugs die is truly amazing. I have many many weekends competing where I went through that many by Saturday afternoon final rounds.

Of course when I was younger I did not know near as much as I do now and in the last ten years I too do not have a notably high failure rate. That said, I do have many original or new production "Correct" glow heads for most of my Cox engines. Still, due to their cost, I only run and fly with the Merlin or Nelson products and preserve the original glow heads for my grand-kids to make some scratch if or when they sell off my collection

pkrankow Mon May 13, 2013 9:47 am

I enjoy a low failure rate too. Most of my glow plugs/heads die from mechanical damage such as a bent post instead of the coil going bad. I am not sure what to credit this to. Growing up I recall very few burn out plugs too.

I recently destroyed a plug by dropping my battery which ripped the glow driver off. The post was bent by this. The real thing was I tried to straighten the post, which broke the post off.

I find this clip
http://coxengines.ca/cox-glow-plug-clip-tweezer-style.html
does less damage from getting improperly removed compared to this type
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXUC32&P=7

Phil

straitnickel Tue Dec 20, 2016 11:18 pm

SuperDave wrote:Fred:

I like the appearance of the OEM TD .049-.051 Cox glo-head and recently purchase of pair of them from Bernie @12.50 each. Call it a matter of personal preference.

One was used to replace an incorrect head on a .051 and the other is simply a spare. It seems in all my years in modeling I've had maybe five glo's ever go bad.

SD

Is there such a thing as having a medallion cylinder machined into a TD?

fredvon4 Wed Dec 21, 2016 10:11 am

If you are asking about changing a #2 Cylinder porting to be the same as a #4 Porting?
Yes it is entirely possible with the correct tools.... in this case, I think some real good holding fixture for the cylinder and a good precision Lathe or Mill with the correct size cutters

But since good TeeDee like cylinder and piston are available I doubt worth the hassle... unless one already had the tooling and just wanted to carve steel

I have had some success lightly polishing out machining grooves in tiny Cox boost ports with a Dremel but that experience tells me a Dremel would not be a good tool to try and cut in the right width, depth and length ports

straitnickel Wed Dec 21, 2016 1:11 pm

fredvon4 wrote:If you are asking about changing a #2 Cylinder porting to be the same as a #4 Porting?
Yes it is entirely possible with the correct tools.... in this case, I think some real good holding fixture for the cylinder and a good precision Lathe or Mill with the correct size cutters

But since good TeeDee like cylinder and piston are available I doubt worth the hassle... unless one already had the tooling and just wanted to carve steel

I have had some success lightly polishing out machining grooves in tiny Cox boost ports with a Dremel but that experience tells me a Dremel would not be a good tool to try and cut in the right width, depth and length ports

okay I suppose I should have mentioned this is about a .15 not .049

**Cribbs74** Wed Dec 21, 2016 8:49 pm

Yeah that would have made a difference... Very Happy

So you want to make a medallion .15 cylinder the same as a TD .15? As far as I know they are both dual bypass cylinders.

straitnickel Wed Dec 21, 2016 9:01 pm

Cribbs74 wrote:Yeah that would have made a difference...

So you want to make a medallion .15 cylinder the same as a TD .15? As far as I know they are both dual bypass cylinders.

I thought so too, but this Medallion I picked up on ebay is a single port, it could have been swapped and with next to no chance of finding a lone cylinder I'm looking into the possibility there is someone who does this type of work.

**Cribbs74** Wed Dec 21, 2016 9:28 pm

Well, the Sportsman .15 was a single bypass. I don't have a Medallion .15 to compare.

Makes no difference to your question though, so yes it can be done by a competent machinest pretty easily.

Ron

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