.15 Medallion Engine

Looks good.

What do you plan to use it on? The spray bar from the Medallion won't help it breathe any better although the Medallion venturi may help it draw fuel more consistently.
Ron

Three Draw backs about it is 1. there is no Starter spring, 2. No prop screw, 3. No prop. I sure do not want to start it with out one. Because if i did when the prop kicks back and the prop hits my finger the force might break my finger.

It's highly unlikely you will break your finger. It's going to hurt mind you. The Medallion is a pretty timid engine. I wouldn't recommend sticking your finger in the engine while it's running. I've done this many times in racing events. It does hurt and leaves a nice mark when it does happen. Wear a glove to start the engine. The nylon and composite glass props should have all flash removed and sanded lightly with fine sandpaper. Rather than flip the engine in a conventional manner from right to left (counterclockwise), once the engine is primed rotate the prop clockwise until you feel a slight bit of compression. At this point, give the prop a quick smack backwards (clockwise). This also quickly clears a flooded engine. While it seems incorrect to flip the engine in reverse, it hits the compression stroke and runs forward assuming the engine isn't overprimed. This technique is known as back flipping or bump starting. A much safer and easier way to start almost any engine. Ken

I've found that compression bumping is the best way to start all of my Tee Dees. And after recently getting used to starting my larger engines with a chicken stick, it's always in my pocket at the field, so I've been using it to crank the little springless ones too. I just slipped a piece of automotive fuel hose over a philips screwdriver, now it's a chicken stick. Just don't bend your needle with it. That's where the short tipped commercially purchased sticks are better.

In my opinion a Medallion with a Tee Dee front end, is just a finicky Medallion that's harder to start, needle and feed than it originally was.  It was intended to be a more cooperative sport engine, and the architecture of the crankshaft assures this, no matter what sort of intake supplies it.

There's no evidence that sprinkler venturis produce higher performance than through the throat type spraybars. The through-the-throat venturis are wider to make up for the volume lost to the spraybar. On the other hand, a  Tee Dee with a Medallion front end might make a powerful, easier to handle engine for sport use.

These are just my thoughts, I haven't tried any of the combinations, but I believe it should be true. However, try it and let us know how it really works out
Rusty

Yes the spray bar in the center of the venturi does help to aspirate and draw fuel in lieu of a smaller intake bored into the crank shaft. This is a large enough engine the round hole in the crankshaft should be big enough to perform well and if you sharpen the cranks intake holes edge on the right side it will increase suction. Sourcing a OEM TD crank shaft is next to impossible so only thing is to mod yourself. I have ran it on the bench it fired up with ease with a elect starter. I ran it rich about 5min as the engine had never been run and the throttle sleeve was closed about half way to keep the rpm down with the yellow Tornado 7x8 prop.  Also during my mods I had added a phenolic thrust washer.
Note the data Plastic venturi is 13.5mm OD and 11mm ID at the lip the Aluminum is 15 OD x14 ID mm at the lip.

Thank you. I need to fix up a test stand for it.

I don't Know. It is going to be part of my collection of Cox Engines. I really would like to have Order #3704 Queen Bee .074 for my collection.

There are springs on ebay for the 15 size motor and spinner and bolt assembly to help you on your way.

I will be looking for that.

Hello,
i have to see that you have modified one Medallion Cox engine with the part of Tee Dee .15.
You think that i can do the same with one Medallion .09 ? I can change the original Red carburetor body with the carburetor body of Tee Dee .09 ?
Let me know.

Thanks and Regards
Jorigger - Italy

I used the aluminum carb body sold by an ebay member Mike (Ridingfly) if I recall. Inside the aluminum carb body is smooth with no protruding plastic that plastic may need to be worked down some if you choose to use a stock td carb. But yes it should work.   I may open up the intake on the crank with a dremel tool some, yet  on a 15 engine there is really already more than enough power to weight.

1/2A Nut wrote:I used the aluminum carb body sold by an ebay member Mike (Ridingfly) if I recall. Inside the aluminum carb body is smooth with no protruding plastic that plastic may need to be worked down some if you choose to use a stock td carb. But yes it should work.   I may open up the intake on the crank with a dremel tool some, yet  on a 15 engine there is really already more than enough power to weight.

Hello,
Thank you very much for the quick response. I know this'' Mike'' (Ridingfly) that sells carburetor body made ​​of aluminum. I have already bought by him two, one for a cox .049 and one for a Cox .020. They are of excellent quality items and material.

The only thing i did not understand from your answer, is the question on the small logo Cox. Be more clear.

Thanks again and Regards

  The medallion crank intake is round vs the td has a larger square shape intake by opening this up some you can increase the air / fuel mix for more power.