There were several makes of diesel that used this eccentric bushing approach to compression adjustment produced in the late 40s-the French Ouragon, the Norwegian David Andersen and the British Airstar. I suppose the manufacturers thought that by making compression adjustment similar to advancing the ignition timing on an ignition engine there would be greater market acceptance. ......and not forgetting the little British Telco CO2 motor-which alone among CO2 motors-used the same eccentric bush adjustment to alter the engine speed.
From a production standpoint, though it would seem to require much more critical machining of the crankcase than conventional adjustment via a screw in the head...........the degree of eccentricity, the fit of the bushing to the case.....

ChrisM
'ffkiwi'