ORIGINAL: D Bronk
..At this point ,no more horseing around with the venturis,untill I can find more Rpms, somewhere else.Then I`ll look at that Dept. again..
But don't we all "know" there is something there.
Back when many CL Combat flyers were serious about Slow Combat I messed with venturis a bunch.
The rule in Slow was that you could not use a pressure fuel system. Yes, yes, I know - suction fuel in a Combat (or other high G) plane is dumb thinkin', but it was the rule.
So you needed a setup that would draw fuel when street variety suckin' just would not hack it. Chrome off bumpers and all that . . .
The best venturi I ever tried was a 'post' venturi. Actually the venturi itself was pretty standard, but the fuel spigot was a post that stuck out in the middle of the venturi and deposited the fuel in the middle of the airstream.
I tested many venturis on a simple setup that used the vacuum cleaner for suction and measured the effectiveness of the venturi by how far it would pull water vertically up a clear fuel line.
The good ones looked something like your reject.