ChiltonLibrary in the databases, but the diagram that came up showed a round piston. We went to Google Images and found a picture that showed him exactly what he needed to know.
I've found that when a schematic or diagram for any kind of engine (especially small engines that aren't covered in Chilton) is wanted, Google Images can be a great tool for finding it. Had this failed, I would have tried to do a search through one or more of the Oldsmobile online forums to see if this question had been addressed by someone previously.
Springville Road Library