I think we’ve found a good path forward on the crankshaft. Unfortunately, new Super 90 crankshafts are not to be had anymore. There were more legitimate choices than I would have guessed:
- Keep the SPG roller crank that we found in the engine
- Buy a SCAT crank for just shy of $2500
- Buy an “economical” aftermarket crank such as AA Performance Products for around $1400
- Buy a new Porsche crank. Sunset Porsche says you can have a new Porsche factory crankshaft for only $3,536.85
- Find an original Porsche crankshaft with reasonable dimensions that can be polished and / or ground
Not a clear winner in this list based on my very limited experience. Ultimately, we decided to use an original Porsche 356SC / 912 counterbalanced crank. The used Super 90 cranks floating around have already been ground beyond a comfortable tolerance to continue using. The 912 crank is not likely to be any cheaper than the AA crank, but Soren is confident that after checking dimensions and magnuflux testing we can have good confidence in the reliability even though it’s used. It’s also a factory part.
The main concern with used cranks appear to be cracks, which ultimately lead to you having a “two-piece crank syndrome” in your prime mover, as The Maestro would say. Not good! Soren’s initial evaluation involved lightly tapping the end of the crank on the concrete floor. It rang like crystal. Apparently a cracked crank results in a much duller sound. He of course did measurements as well. That said, we’ll invest the $50 or so to magnaflux the crank. The peace of mind will be well worth the cost.
Funny side note. I found a 356 Registry from July 1978. For Sale entry asks: Crankshaft PN 616.102.015.00 new, still in original wrapper. found in trash at local dealer. Is it worth $35 or will take nearest oiler. A1 Moreland 601-555-3716
