Randy here is that stuff on the Ellison carb.

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Here is some stuff from back in the days we were considering
incorporating the Ellison idea into our stock Teflon slide
throttle. What discouraged us was the cost quotes we received
on the laser cut holes. If you can find someone to cut all the holes
this is a real good way to go.

Paul Lamar

Paul, or anyone, is it critical for the holes in the tube to be oriented
in any
spedific way, like radially to the tube axis, or can they all be
oriented to one
plane?
Just asking, a friend of mine has a laser machine for etching granite.
It has a
YAG laser if I recall, probably plenty of power to make holes in brass
tube. If
you guys are interested in pursuing this route, I was going to ask for a
bid.
C. Smith

You change the hole pattern at your own peril :)

I think it is largely empirical.

That is a complicated air flow field inside that throat.
Note the Rotec is an exact copy.


Paul Lamar


Greetings all,

I may be talking completely about another subject as I have not been
following this string.

If you are talking about the holes in the brass tube which spans the
throat of the Ellison, their orientation is critical.

The way Ellison adjusts the mixture is by varying the orientation of
these holes with respect to the airstream going through the throat.

When the holes are orientated into the oncoming airflow, the unit is
essentially at idle cutoff. As the tube is rotated, with respect to the
airflow. more and more relative vacuum is created over the holes. As the
orientation of the holes goes from into the airstream to 90 degrees to
the stream the relative vacuum increases from almost 0, (actually
positive)  (idle cutoff) to maximum (full rich). The control lever, for
mixture, merely rotates that tube to achieve these results. The throttle
slide controls the amount of air passing. As it opens, more holes are
uncovered. The mixture function is the same, independent of throat opening.

Rich

Very well explained Rich.
Randy has a spare I am going to copy.


Paul Lamar