An apparatus for filling cans with a liquid such as beer or soft drinks. The filling machine includes a turntable having a surface to support a plurality of open top cans and a reservoir containing a liquid is spaced above the supporting surface. A plurality of filling heads are mounted on the reservoir and serve to dispense the liquid into the individual cans. Each filling head includes a spring loaded cylindrical tulip adapted to seal against the upper edge of the can and a vent tube and fill tube are disposed concentrically within the tulip. The lower end of the vent tube communicates with the can while the upper end is sealed against the surface of the reservoir and when the sealing engagement is released the vent tube communicates with the headspace of the reservoir. The lower end of the fill tube carries a valve that controls flow of liquid from the reservoir into the can. After the tulip seals against the can, pure carbon dioxide is introduced into the can from a separate reservoir and air is vented from the can to the atmosphere. A differential in force acting against opposite ends of the vent tube will act to lower the vent tube into the can and the valve is opened to admit liquid to the can with the gas from the can being discharged through the vent tube to the reservoir headspace. When the liquid rises in the can to the level of the vent tube, the liquid will move partially up within the vent tube. The vent tube is elevated to compress the gas therein and force the liquid out of the vent tube. The gas is then released from the head space of the can to the atmosphere.