an ink knife duct - adjusting screw unit for an ink fountain in a printing press , having a contact pressure bolt engaging in the bore hole of the housing of an ink fountain and acting upon the ink knife , and a device indicating the position of the duct - adjusting screw and having a control lever . the duct - adjusting screw unit has a modified adaptor element which can be inserted into the existing threaded bore holes of the housing of an existing ink fountain . the remaining elements of the duct - adjusting screw unit can be used according to the type of the machine .