Dave,


Cost may have been one reason for discontinuing production of this carburettor, however, the newer #3216/3219/3215, with all their various models and variations are probably as linear as the #3222 that your MVVS .91 sports.

The older versions of the same carburettors, had the blunt-end idle needle, that caused the mid-range to be awfully rich, with perfect top and bottom ends.

For a time, an upgrade has been offered (#3216-0253), using the new, tapered needle and a replacement nozzle, but the behavior of the new carburettor is incomparably better than the old, even upgraded version.


The basis of operation of an R/C carburettor is the fuel metering, done by several means.
The basic means is the tapered low-speed needle that moves further into a nozzle, as the throttle is closed (the barrel moves sideways along a guide), making the fuel orifice smaller and allowing the engine to suck less fuel, as it inhales less air, thus achieving a close to ideal mixture, at all throttle openings.

Some carburettors meter the fuel differently, like, for example, the Perry carburettor, the aforementioned #3222 MVVS, the Webra Dynamix and a couple of other designs. Even the so called low-speed needle, works in a different manner in different two-needle carburettor types.