Tim,
if you look at your photos of the oil distributor gasket, you will see three oil holes. The middle one is the valve, the larger of the outside ones feeds the rods and the smaller one feeds the rocker arm. That smaller hole feeds back into the block and comes out where the external oil line emerges in a U bend. That oil line goes through the water jacket and up under the side cover to the rocker arm. On the 216 with the short side cover, the rocker arm is fed from the rear camshaft oil gallery and that line coming through the water jacket doesn't exist. The small exit hole in the block also does not exist. The Inliner filter is made so that the filtered oil can only exit through that hole.
