Howdy

On the Walbro Model MDC Carburetor,
The inital adjustment for idle and high speed
mixture is 3/4 turn open from a lightly seated position.
Make final adjustments with the engine warm and
make sure the air cleaner is clean.

Are you sure about the model number there are some many different/similar ones.

On the Zama model M1 Carburetors.
they start at 1 1/4 turns open.