A filling device for a filling machine configured to fill receptacles with a pourable product, comprising: a tubular body having a longitudinal axis, defining a central flowing channel for the pourable product, and terminating at a lower end with an axial outlet opening adapted to deliver the pourable product to a receptacle to be filled, wherein the channel includes a tapered-section portion located at a given axial distance from, and above, the outlet opening and tapering towards the outlet opening up to a narrowed-section zone; a shutter movable within the channel; and at least one exhaust conduit arranged on an outer circumference than the channel with reference to the longitudinal axis; wherein the channel includes an enlarged-section portion located immediately below the tapered-section portion, having a larger diameter than the narrowed-section zone, and defining an expansion chamber receiving a bottom end opening of the exhaust conduit.