One of those very nice "Stunt" Gentlemen from Texas did some fairly sophisticated vacuum testing about 25 or more years ago on what was the "Sweet Spot" for fuel suction from a single hole needle valve. Memory says it was 5 to 7 degrees off the centerline of the hole in the venturi in either direction. I also remember that it didn' seem to make a lot of difference as long as it was somewhere in the down direction. Just a little better in that particular area!
I think it was Frank Williams but that could be wrong!
Randy Cuberly
Yes, Frank re-ran this testing after I published the article I mentioned above. The result is not "off the centerline" but just off perpendicular.
The testing showed that there is a sweet-spot of just a very small rotation where the "suction" suddenly jumps, by on the order of 12%-15%, and that if the hole is positioned anywhere else (downstream) there just isn't any significant difference. Only at the "sweet-spot".
It's almost impossible to find the sweet-spot my just looking at the valve body in the venturi, so, as I said, just put the hole somewhere out of sight and you get what is available.
Now one must consider the old Fox 2-hole needle valve body. The holes weren't drilled directly opposite. Kind of wonder why. Maybe Duke realized that if you put the needle valve in so that the two holes were just about out of sight and "looked" the same to the eye, maybe they would find the "sweet-spot". Maybe ....
Topic: spary bar with ONE hole in it. (Read 1159 times)
