Research seems to confirm my suspicions that the crank was not correct, much less original.
Courtesy of the late great Harry Pellow’s book The ABC’s (and 912’s) of Porsche Engines or Porsche Engines and the Future of the Human Race, the early Super 90 did have a unique crankshaft. Mainly just a beefier main bearing journal diameter of 55mm. Mine being an early S90, would not have been counterbalanced. It looks like the counterbalanced version did not cut in until about #803000. Our engine is #800698.
So what to do about a crank now. I suspose I should try to ID the existing one first. A brief bit of research shows that Super 90 crankshafts are no longer available, even as a reproduction. Used they seem to sell for North of $2,000. And then, I suspect you’re taking a leap of faith that they’re good.
This is an unexpected challenge…
