I am still hassling with the TBI40(Ellison) unit.

First some general comments. The engine is running without any
issues, after the oil spitting was fixed. I am thinking now of doing
away with the oil separator, because both engines, the one on the
test stand and the one in the airplane are bone dry on the breather
hose. Cooling is just fine. always the same temperature, 170 F
coolant and oil with doing takeoff runs to air speed over rotation
speed, as often as I want to.

So, Why do I not fly? Back to the top! When Rotec copied the Ellison,
they realized the importance of the fuel section between the pressure
regulator and the spray tube. They separated the pressure regulator
as a free standing unit to be located as required depending on the
way the TB is mounted. The installation instructions are pointing
this out in a, for my taste vague way(makes me not look as ignorant
as I might be).

Anyway, the apparent problem I am observing was never serious enough
to give up considering the alternatives. And this on top of my
stubbornness. One issue is the fact that on the rotary, in particular
with a P-Port, the intake is cross draft and an as short as possible
distance between the throttle and the intake port in the rotor
housing. Adding a limited space under the cowling in this area,
requires an orientation of the TBI40 suitable to confuse the
installation instruction.

In a nutshell, I had to separate out what is a mixture issue and what
is a fuel flow issue. As it seems to turn out, it is more of a fuel
problem. mixture is always pretty good.

When I orient the TBI40 in a way so it is running right, it beats any
carburetor I have been running in the past 5 years. Hopefully
tomorrow I will run the final tests for having a flight worthy
installation configuration.


Richard Sohn N2071U

http://www.fairpoint.net/~res12/home.html

Thanks for the update.

I am in Fl Richard and you are up early. :) Are you coming to Sun n
Fun this year?

Here is an idea. What slowed me down was the cost of all those tiny
laser cut holes :)

Paul Lamar

Paul,

The Ellison carb is really very intriguing…small, simple and
lightweight. How small do the holes in an Ellison-type carburetor
tubing need to be? Wire sized drills can go down to 0.0135 inches,
which is almost 5 times smaller than 1/16 inch. That's pretty darn
small! Is laser drilling really necessary?

Gene Kahn

I measured the Ellison [?] carburetor hole sizes compared with the outside orifice opening
size from the picture.  The orifice opening was 140.7 times as big as the hole size [hole
size from picture 0.7mm, orifice size from picture 98.5 mm].  So if the actual orifice size
was, say, 2 inches, then a drill size of  [2][0.7]/[98.5] = 0.0142 inches.  That is larger than
the smallest wire drill size of 0.0135 inches!

Gene Kahn



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