layback2

My Feedback: (12)

OK you COX Guys here is a engine i got last week and need to know is it a TD or medallion .049 how can i be sure what it is

skaliwag

My Feedback: (1)

It's a Medalion.. The TD has a take apart Venturi.

Andrew

Medallion

Check out [link=http://www.mh-aerotools.de/airfoils/cox_frameset.htm]Martin Hepperle's site[/link] for extensive COX information.

gcb

Wow! That is a good question. At first I thought it was a Medallion because of the venturi housing, but then I noticed the gold thrust plate. If it has two bypass ports, I would think it is a TD with a Medallion venturi assembly. But then, it could have a TD replacement cylinder... [&o]

George

Jim Thomerson

One can find exceptions to most any rule about how Cox engines are put together. I'd think it is a Medallion.

layback2

My Feedback: (12)

How do i check to see if it has two bypass ports can you tell me what to do to check thanks

gcb

Normally, you would look into one of the exhaust ports for machining on the part between the exhaust slots. The machined slots are the bypasses. The Medallion has a slot on one side, the TD has a slot on both sides. I believe at the last, all cylinders had two bypasses.

Since you have a throttle sleeve on yours, you can remove the glow plug (TD, by the way) and look into the top of the cylinder (with piston down) and check.

George

Edit: Additional thought. The prop washer and screw may not be standard on that engine. I think all TD's and Medallions in the .049/.051 range used the "cone" type spinner with the screw. Also check that the screw is the proper size.

ZAGNUT

My Feedback: (1)

all the medallions i've ever seen (back into the '80s) had twin bypass ports and large exhaust ports with SPI, same cylinder as the black widows. the older TDs had the two extra cuts on each bypass to enlarge them while the newer TDs only had one extra cut per bypass like the sure-starts.

it also has a TD plug on it along with the gold prop driver so who really knows what it is....


dave

gcb

I just checked and my Medallion .049, bought new many years ago, has a single bypass. It does have sub-piston induction.

BTW, I don't mean to imply that all Medallion .049's are like mine. Mine is an early one.

The older TD's also had extra machining like a tapered bore. Some of these operations were dropped due to production costs. Since Cox was doing a lot of mix and match, the newer TD's you refer to may have indeed had the same cylinder as the Sure Start.

George

Edit: A couple of Medallion pics. Note the aluminum thrust plate.

layback2

My Feedback: (12)

I check it has two bypasss and large exhaust ports plus a number 3 stamped on the bottom of the cylinder i was looking at this TD.051 looks alike like my engine not sure

ZAGNUT

My Feedback: (1)

gcb, look how the cylinder in your pics has a smaller outside diameter around the exhaust area than at the base. i've only seen this on real old engines and with the single bypass it must be real low on power. pretty sure they stopped making those cylinders in the '70s.


layback, two bypass ports doesn't mean a whole lot as all modern coxs have that.

here's a couple of things to look at:

if the piston skirt has a small groove all the way around then it is a TD .051.

if the bypass ports have an extra groove on each side then it's a TD .049.

does the bottom of the piston skirt rise above the bottom edge of the exhaust port at TDC?





dave

Luna_Rendezvous

lb2...

As parts for tee dee's become more difficult to find, there seems to be a lot of parts swapping going on, but the main differentiator between the medallion and tee dee is the crankshaft. On the photos below you can see the square machined opening along the axis of the crank where the fuel air mixture enters the crank to be transferred to the case.... on Tee Dees this opening is a large rectangular slot, on Medallions it is a smaller circular hole.

Below are photos of crankshaft, venturi, carby body, with needle valve and assembly from one my .049 Tee Dee's

Hope this info helps,
Regards mike.

Remby

My Feedback: (3)

The crankshaft Mike shows above will add more power over a Medallions with the round intake opening. The ones made after 1973 have improved timing over the older ones.

MJD

My Feedback: (1)

Mostly because TD .051's were made with red plastic parts to distinguish them from the TD .049's which were black. Performance is identical, but (maybe you know this already) the two were designed to be swapped back and forth to allow aircraft to compete in AMA classes 1/2A and A without a change in performance or trim. But look at the venturi assembly and you will see the obvious distinguishing feature which is the venturi design. And that said, it could easily be a parts engine as suggested.

MJD

gcb

We seem to keep going back to the cylinders so here is some info. Remember Cox sometimes mixed and matched so it may not be totally correct. I understand this info was to help Cox sort parts. This was from Joe Klause, some time ago.

No.1. A two bypass cylinder with a large exhaust port that permitted sub-piston induction. It was originally made for the 290 and 291 series engines that were used in plastic cars later. It was used in the first Black Widow engines. At that time the top cylinder fin was not milled to accommodate a maintenance wrench. Subsequently, the Black Widow I cylinder had two narrow slits for each I exhaust, and the top fin was milled, but the cylinder was not numbered in this configuration.

No.2. This denoted a single bypass. sub-piston induction cylinder. The top fin was not milled. This type was used on the Golden Bee, however, the cylinders were not always numbered.

No.3. A two bypass cylinder that initially did not have the bottom of the exhaust ports milled low enough to pro- vide sub-piston induction. Later, the exhaust milling permitted sub-piston induction, and the outside was ground for use with an exhaust-restrictor type throttle, and the top fin was milled.

No.4. This was made for TD .049 engine. There are two bypasses, each with three separate milling cuts and the bore is tapered. The exhausts allow sub-piston induction and the top fin is milled.

No.5. This has the same features as number 4, however, the bore is .410 inches. It is used on the TD .051.

No.6. Twin bypass, no sub-piston induction. and milled top fin. Some were externally ground for restrictor throttles.

No.7. The same as number 2, but with a milled top fin.

No.8. Single bypass. narrow exhaust, no sub-piston induction. Top fin not milled. Used in cars.

No.9. Unfortunately, I do not have samples of this cylinder. My only information is that it was only in very limited production.

No.0. Again. I have no samples, but it reputedly is the same as number 6.

George

Remby

My Feedback: (3)

Old (1960s-70s) Medallions did come with SPI, and single bypass porting, with open exhaust ports. The later ones can and did have cylinders like the sure start.

chevy43

removed post....

layback2

My Feedback: (12)

To all who answerd this post the engine was a medallion with switched parts from a TD but with a little help i found the original parts now it is what i thought i bought in the first place thank you all for the great info