Not long ago, I posted part of Leonard Neumann's (sp?) venturi chart in another thread. No, I don't recall what size engines the section of the chart was for. But in general, .272" bore with a .156" spraybar (AKA 4mm) is a good
start, which can be easily toned down with a few layers of nylon mesh trimmed from 2nd hand pantyhose. Tim does this, himself.
The interesting thing is that a .272" bore with .156" spraybar through on center is a good start on .25 to .76 engines, because the bigger engines pump more air through the same throat area. Perfect, no. But it saves a lot of math. I've used .272"/.156" on .25LA, XLS .36, and .46LA engines. My PA .51...dunno. OS .46VF...dunno. PA has the offset spraybar like a lot of Super Tigres did, so the bore is much smaller, and I don't recall what it is, but I think the .46VF is .272", but it's a Randy Aero engine, and I haven't checked the venturi bore.
I'd kinda like to post the whole chart once and have it "pinned", but it's not up to me. I have the file, if anybody can pin it someplace. I've reworked it some to try and get the columns straight and the column headers lined up. Frustrating, the computer program used didn't like that, but it's better than it was. Numbers are the same, all I did was put a lot of time into fine-tuning the chart a little to make it easier to read...multiple pages of it. <sigh>
Frankly, I strongly dislike "clicker" type NV assemblies, most especially the OS ones. Yes, they work nice while they work nice. But they can be damaged, look ok, but don't work worth a spit. I'd rather have them look broken when they're broken! I'm hoping you'll play with the ones you have, if you like them. Randy's are the best!
Steve