Gents,

The Oldest Taurus on Earth was the discovery of a plane that was forgotten in the past.

Are there more examples of that? Yes, a nearly same story, read!

My Orion does fly with the “very” old ENYA 60 4 C, Maybe 30 years old, but, it’s now a very reliable engine.
I bought it second hand in very bad condition, for “no money”.(Cheap!)
The gas plant is a bleed air carburetor with a simple fuel metering system and this were results of a study!

ONE

The internal diameter of the air duct in the barrel of the carburetor is 5,5 mm and the bore of the air duct in the carburetor housing is 7 mm? (See picture 1)
When changing diameters in an air duct the problem is, friction factor, so drag.
The ratio of surfaces is: 5,5 x 5,5 / 7 x 7 = 0,62!!
When you do it twice, contraction and expansion ? Indeed, double of all the drag.
Picture 2, after making a nice throat in the barrel, the result is a better airflow, a lower resistance and still the same sucking pressure.
Also the recovery of the low pressure after the carburetor will be much better, so results in more inlet pressure of the engine.

TWO

Such a fat piece of metal tube in the centre of the duct they call a nozzle?
Turbulence and drag is the result again, see the compare picture 2.
I did remove all the “too much” material of the nozzle in the throat and give it a better shape, so less resistance and still the same sucking pressure!.

THREE

The carburetor of the Enya 60 4 C does have a, not adjustable, fuel metering system. A sleeve in the outside of the barrel to restrict the fuel flow depending of the position of the throttle. (see picture 4)

But:

What about when they did use the 2 stroke carburetor? The 2 stroke carburetor with a smaller bore in the barrel? A carburetor for a exhaust pressurized fuel tank in the past? To reduce engineering costs?

I think they did, so after many years of operating for another owner, I did change the carburetor.

I did make a direct fuel connection on the barrel that rotate with the barrel, the flexible fuel line will fix the movement. See picture 3
Result! No unknown fuel flows in the carburetor on other places than through the nozzle!! No metering anymore because we have fuel pressure control! No more unknown restrictions. Better constant ratio of fuel and air over the power range.

The story.

I did exactly the same with the, on that moment about 25 years old, carburetor of the Old Enya 4 stroke as is done with the Oldest Taurus on Earth, the first contest Taurus by Ed Kazmirski. Change many things!!
As many of us know, Ed was an inventor and did change any product he did have, so also the First Contest Taurus.
Only when you know the process you recognize the Oldest Taurus on Earth on the crate picture as I always recognize the original metering barrel of a ENYA 60 4 C.

Because I also do have an original new engine and the “modified” old one, I can put both situations on the pictures without photo shopping!!!

The results for the engine?.

This engine runs without any problem full range, reliable throttle without on board glow plug battery.
It starts with one flip of the propeller without any dead stick, nor “backfire”.
The engine is very powerful because of the better breathing, probably also because of the diffuser cooling!!

Our hobby, always something to discover and “Baat het niet , het schaadt ook niet!” (Again the Dutch proverb)

Ed Kazmirski did the same with his first contest Taurus as I did with my first four stroke engine, make it better any time!

More to come!

Cees