The installation comprises an extruder (12) of which the extrusion screw (36) may be axially displaced, a number of moulds (14) arranged horizontally in a molding loop (16), of which a plate (74) may be displaced on its threaded axis (78), thereby bringing the moulds (14) into successive positions of filling, consolidation, cooling and mould removing. A material sensor (53) positioned at an adjustable distance from the rear end of the mould (14) can stop the filling cycle, elastic means (88) being provided for the sealing of the mould (14) after its filling and a device (94, 96) receiving the casting after unmoulding.