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Here we have the classic problem of obtaining information from the internet for an engine that has seen many years of development changes. Compare the last photo you posted with the crankshaft in this photoThe shape of the counterweights of the inside webs are quite different. Both are correct, but clearly from different times in the engine's development history. Unless you have access to an individual engine, an exact replica may not be possible. With the information resources available to us and the need to make the engine do-able in the home shop, the best we can hope for is a near scale model. That said, a near scale model of the Porsche 917 engine is going to be something mighty special, an incredible challenge both to design and to make. But what an engine it would be when you get there. Stick with it Dave.Mike
By the way, castings are rarely harmed in my workshop.
I used to find, before I realised the importance of casting fondling, that sometimes I would get different features than shown on the drawing . Jo
Been thinking about that Mike. Is bet the photo I posted was to a turbo 917. It would make perfect sense.