Same with "SU" and "Stromberg" carburettors (to example Volvo, Saab and english cars) has not accelerator pump and they has meterings needle.

A common "butterfly" carburator has not enough fuel between idle and full trottle when opening from idle to full trottle, therefore it has accelerator pump to give extra fuel there are not enough fuel.

I has Webra T-4 with Dynamix carburator, works well, but it is not big difference between common R/C carburator and Dynamix carburator.

Jens Eirik