Dyno results - Tquad vs Holley vs Qjet - tuning issue, too rich
There is no logic to removing the outer venturi on a Carter solid fuel metering carb. If its the early emulsion design I can understand it as it now becomes a single stage booster like a Holley and you can use air bleeding to get the booster to come on sooner but the design of the the triple venturi is such that it creates so much vacuum that no air is required to get the booster flowing at lower rpms and therefore no air bleeding to interupt the fuel flow. Essentially you get air and fuel mixed together out of the booster of a Holley so some cylinders get more fuel or air depending on how well its entrained. The Carter does it with the fast moving air in the primary booster so the air gets fuel not fuel and air. Now think about what that does to the distribution between cylinders.
This is what the original inventor had to say about its efficacy:
"The fuel is conveyed from the restricted orifice in the jet member 28 through a cross bore 34 into a vertical bore 35 and from this bore the fuel flows through a cross bore 36 into the nozzle chamber and on up through the nozzle 27 through which it is discharged into the venturi 20.
The fuel comes out of this nozzle with some velocity and is discharged into the most rapidly moving portion of the air stream as it passes through the venturi 20.
The walls of this venturi serve as baffles to straighten out the flow; of the fuel. thereby preventing it from striking the walls of the air chamber or the conduit 8 until after it has been vaporized by additional air entering the venturis '19 and 7. I consider this an important feature of the invention, for tests have shown that when liquid fuel is per mitted to strike the outer wall of the mixing conduit, it is likely to be carried along in liquid form by the air stream in such a way that vaporization and distribution are not efficiently accomplished.
By the above arrangement, I am enabled to avoid the necessity for mixing air with the fuel in the fuel passageways and nozzles which would cause the delivery of the fuel in slugs and generally inefficient operation of the carburetor, particularly at low speeds."
So the triple booster design offers better vaporization and distribution and since you tune to the weakest cylinder........
And that was 1930!