Weber info about Aux Venturi

[patty442]

Mr. Priobe. It does make a difference. Real difference in driveability at your cross over point, especially. 3500 to 6500 rpm is way past that point and does not make a difference that other contributors can feel in a 400 h.p. 289.. Cutting them off shorter is usually for hood clearance issues but
some "smart" guys in California think there is a performance gain. We don't because we haven't seen it. We have worked extensively with auxillary venturis and their effect on overall performace, performance in specific RPM ranges, and under different loads conditions. We have worn out two 675 h.p. FE motors on the dyno, testing. We have installed and tested many, many combinations in a borrowed 4000 car before installing the final results in our original 3000 race car. We have tried original 4.5, 4.0, and 3.5 auxillary venturi and have seen the changes in main circuit activation in both timing and strength. We have tried 4.5's cut at 1/4 inch intervals. Almost to the nonsense cuts that you pictured. We even found a 3.0 set which received the same cycling on both the dyno and our test car. As our 4.0, 3.5, and 3.0 auxillary venturis are made from unobtanium, my best suggestion for you is to stay with the 4.5 uncut and go from there. I must add that we do NOT use the 4.5 in our final set up. Hope this helps