Given how specific Porsche is with their parts and tolerances, I was shocked that there is no definition of spark plug torque value. Not in the manual, or to be found on the 356 Registry Porsche 356 Bolt & Nut Sizes and Torque Values article.
I did find a link to the NGK website, which does offer some spark plug torque guidance. This would be helpful, but our model of plug is not listed! So more homework required. We’re using NGK BP6HS 7331, based on some suggestions from a Spark Plug Recommendation article at the 356 registry. This is a 14mm diameter plug, which suggest 25 to 30N·m (2.5 to 3.0 kgm). Well we’re in the US, so one more conversion to ft lbs. That yields 18 – 22 ft lbs.
As a side note, Harry Pellow says on his tape he likes Bosch Extended tip W200 T35 or W225 plugs. He mentions a T7 side electrode for use on Super 90. I’ll have to research that.
