Engine Components-911/964/993 PMO Carburetors 40mm 46mm 50mm
The PMO carburetor was designed from the beginning to be a state-of-the art carburetor. PMO start off with a casting designed around a 50mm throttle plate and downsized to 46 and 40mm to achieve three different sizes. This compares favorably with conventional carburetors, including Weber.
The air entry and flow is much greater than the Weber. This is accomplished by having larger main barrels in the throttle body, tapering the top covers and then installing larger diameter velocity stacks of corresponding taper. This maintains the boost from the velocity stacks down to the exact point where it operates on the auxiliary venturis.
Flow through the carburetor is also optimized by many additional details such as having the accelerator nozzles barely protrude out in the air stream. The wings on the auxiliary venturis are CAD designed using a mathematical formula for an aerodynamic ellipse. Even the throttle plate screws are specially designed with a small Torx head and the exact length to engage all the threads in the throttle shaft but not protrude out into the airflow.
The main jets, emulsion tubes and air jets are in one stack in the center of the casting. This allows fuel to be drawn from the center eliminating fuel starvation in the turns.
The carburetor uses standard Weber main and air jets found in the Weber IDF, DCOE and 48 IDA. PMO added a replaceable idle air jet to more finely tune the idle circuit.
PMO redesigned the accelerator circuit to cause less air flow turbulence and still be more efficient. The accelerator nozzles barely protrude out into the airflow and are aimed at the curved surface of the auxiliary venturi tube. This shatters the fuel stream allowing complete atomization before the air-fuel mixture even leaves the carburetor. The increased efficiency allows less fuel to give the same effect. PMO have a complete selection of float bowl check valves to fine tune the accelerator circuit output to the demands of the engine