in dependence on the air flow rate as transduced by the air flow rate meter 37 the height i e the radial distance of the control surface from the shaft 28 then defines the maximum fuel quantity associated with the pairs of values of the primary variables this maximum fuel quantity is determined for each engine by experiments in which the important criteria may be the smoke limit and or other parameters which affect the performance of the engine the exact manner of associating a fuel quantity with engine variables will be further described below with the aid of fig4 in a second exemplary embodiment of the invention illustrated in fig2 those elements which retain similar functions have been provided with the same reference numerals as were used in fig1 in this embodiment the three dimensional cam 26 is rotated by a control element 41 which displaces a rack 42 engaging a pinion 53 the control governor 41 is shown to be a centrifugal governor but it may also be another rpm dependent transducer for example a hydraulic piston the cam 26 of this embodiment also has a stepped off portion 38 for providing an excess starting quantity and an elastic drag link 43 permits a locking of the cam follower behind the stepped off portion 38 for the purpose of providing the excess fuel quantity in a manner similar to that explained with respect to the operation of the first exemplary embodiment of fig1 in this embodiment the intermediate lever 16 which is coupled to the.