Guys,
I have searched this forum for information on the effect of off-center location of the fuel hole across the venturi diameter, found none. So I put this out. How much off center or off the side of the venturi wall can the spraybar hole be to still get a solid 4-2 type run (not the direction the hole points)? I ask this because some NVA options don't line-up the hole in the center of the venturi and require shimming. How does this off-center location effect the quality of the run? How far off-center can you go without negative results?

Best,   DennisT 

I have a friend who at one point built venturis for Fox engines with the hole off center towards the left, very near the side.  It worked fine on a profile fuselage in that the tank didn't have to be raised of offset burps and rich outside maneuvers.

An off center fuel hole in the needle valve doesn't seem to have as much effect.  Most of the mass flowing through the hole is air, and the flow around a needle valve across it is anything but laminar.  Often times you'll see fuel and air spitting out if the  venturi stack is too short.  It is best to get everything lined up if possible, otherwise at least make sure the NV can be removed and replace accurately.