The method includes providing a body with an upper mounting surface and a lower end, an interior surface of the body defining a cavity, the cavity including a first inlet and a first outlet in the upper mounting surface and the lower end, respectively, the interior surface including a frustoconical inner surface with a first tapered end that is connected to the first outlet. The method further includes first inserting an adjustable member within the cavity, the adjustable member defining a bore with a second inlet and a second outlet, the adjustable member including a frustoconical external surface with a second tapered end that coaxially aligns with the first tapered end, and first connecting a funnel with a projecting land to the body.