Abstract: An advance arrangement for a fuel injection pump, comprising a housing slidably receiving an advance piston which, in use, cooperates with the fuel injection pump to adjust the timing of fuel delivery by the pump, and, a light load piston associated with the advance piston, the housing supporting an externally accessible, adjustable abutment which cooperates with the light load piston to permit setting of a rest position of the light load piston relative to said housing and thereby to permit adjustment, from the exterior of said housing, of the datum setting from which the advance arrangement adjusts fuel injection timing.