>What is the purpose of flange port enlargement? Should the
>manifold flange port be identical in size to the carburetor
>barrel port? Is it critical that the flange be perfectly
>round etc?
The step that you get when you mount a 36mm throttle over a 32mm hole, yields worse flow figures (higher pressure drop at a given flow), then mounting the 32mm throttle that belonged there.
The step creates turbulence in the flowpath that interferes with the flow going through the port.
The size of the two ports need to be about the same, and flow should not encounter any sharp edges at a transfer from one diameter port to another.
Jarrid