A solid steel threaded bung for the blanking off of the compression change over valve hole, commonly used on the 8-1 and 16-2 models which did not have a change over valve fitted because of the fixed compression ratio.
Great replacement unit. Saved much time and cursing trying to split and service the old unit which was seized solid after years of neglect. Hard to replace items these days. Stationary Engine Parts providing a much valued service so that we can carry on using these older engines (Thwaites Tusker digger dumper/ Petter PH2)