Gordon

Yep,  Parker is another good company.  That should work.

Doug

What do you guys have against this idea? What is wrong
with it?

Paul Lamar

Hi Paul,
there is nothing wrong with it  per se :   but using your reasoning...

What do you have against the Parker valve? What feature is missing that
we need? What is wrong with it?

For:   It is well made, it has the known flow characteristics ,easy
to mount,   easy to operate,   vernier adjustment,   and readily
available.

Using the Parker valve makes the Slide throttle a lot simpler, in that
the leaning feature is remote from the moving slide.
And if you must mess with the needle on your lathe/ mill, then you can
simply dismantle the valve for easy access.

Against:  Its mode of operation is not like that on a "Cessna spam can"
???

Dave McC

Where do I begin?

The long needle valve is also remote from the moving slide.
However you want to keep it as close as possible so
vapor is not made in the fuel line from the valve
to the slide throttle by engine heat.

Anything that you have to twist remotely means
you need a torsionally stiff shaft. That rules out the stock
off the shelf leaning cable with vernier as it's shaft is only about
.1 inches in diameter. It must be that small so the valve
can be out of axial and lateral alignment with the twisting
knob three feet away on the instrument panel. If there is any
wind up in the shaft it makes fine adjustment difficult. It also
must accommodate movement by the engine in it rubber mounts. Sure
a 1/2 inch aluminum tube could be used if you mounted it on the
firewall. Now you have at least two couplings to deal with
and a new knob. Mounting the whole valve on the instrument
panel means you have a longer fuel line to the slide throttle
with more opportunity for fuel vapor accumulation.

The second major problem is it takes too much time to open
fully or close fully. That is a major feature on the long needle
valve. You need to open the valve completely to prime
the engine for starting and close it quickly for shutting off
the engine.

Third, the long needle valves position is obvious from
a glance at the knob sticking out of the instrument panel.
No need to read a small rotating scale.

Forth, pilots don't need to be retrained. Anybody flying a
Cessna "spam can" (I represent that crack :)) will know exactly
how and why it is used.

Paul Lamar ...No rotor no motor.

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