Interesting. Just did my '76 2.0, and yes, they were 14mm - 13 would not fit - and the 14's were a bit loose - but NOT from wear. I'd measure them now with a precision digital caliper, but the valve covers are back on.
I wanted to use a 6 pt. box wrench but only have 12 pt. and loosened them with no problems. Previous valve adjustment by local Porsche dealer - think he used a 1/2" impact wrench to tighten them on last adjustment about 3,000 miles ago......took hammer taps on end of wrench to break the nuts loose.........but no damage to corners on nuts thankfully.......
GN
QUOTE(4x4loyr @ May 22 2020, 04:29 PM)
I'm attempting my first valve adjustment on my '74 2.0 ... and after thinking I finally got an idea as what to do, I was going to loosen the jam nut to move the adjuster screw, and my 13mm wrench does not fit.
A 14mm will fit, but it has a little slack.
I didn't want to go any further without a little input. The motor was rebuilt just before I purchased the car several years ago, but I have zero paperwork on the rebuild.
Any ideas? Suggestions? Or, are these just worn/rounded 13mm nuts?
Thanks