... this is another of those stupid ideas that pops into my head from
time to time ... ignore me if you start laughing too hard!

But ... could a ball-valve work as an off-the-shelf throttle for your
Holly carb setup?

See the following:
http://images1.mcmaster.com/Contents/gfx/large/2693k22p1l.png?ver=19729922

Hog a couple of pounds of excess metal off the above unit(s) and run
your intakes into it (about $70 each, however).

Might be a bit stiff to operate (at least at first)

R.Berglund

A 2 inch ID brass ball valve would have a serious effect on the CG :)


Paul Lamar


Who says it has to be brass? Why not make it from a nice cheap PVC ball
valve. PVC is fuel proof and it shouldn't take too much to prevent it
from getting hot enough to melt. ;-) Just sayin!

A ball valve is not recommended for partial throttle operation. Ball
valves are indicated for on/off operation. Same goes for gate valves.

Mark LaPierre
Registered Linux user No #267004

I would say a gate valve is the same as a slide throttle.
Slide throttles work fine. The Le Mans winning 4 rotor had
a slide throttle.

Paul Lamar

A gate valve is loose in it's guides until it is fully seated.  A slide
valve is fully restrained at all times.  A gate valve will frequently
vibrate in the fluid flow due to vortex shedding causing the setting to
change rendering your carefully adjusted setting to drift.

A ball valve is a poor choice for throttling because they generate huge
turbulence at any setting short of full open, and are notoriously
difficult to adjust to a low flow setting.  Tiny movement results in
large flow percentage change.  In addition there may be an issue with
sucking the seal out of place at part throttle if the valve design is
susceptible to that.

Slide valves are quite effective for use where the valve is lubricated
by the fluid flowing in the system.  The fluid seals the slide due to
viscosity effects in the very small clearance gap between the slide and
the guide.  They require close tolerance machine work to be effective.
The larger the valve the more difficult the construction.

Have you considered cutting the opening in the slide in a teardrop shape to make the idle adjustment less sensitive?

Mark LaPierre
Registerd Linux user No #267004


Yes we tried that and decided it was not worth it.
These are normally punched out with a CNC punch to keep the cost down.

http://www.rotaryeng.net/slide-kit.jpg


Paul Lamar