Tolerance
 

How much tolerance in valve lift is "allowed" between the cams when timing. I have a 69 E and the overlap value is 3,15 mm - I can hit 3,17 and 3,18 - but the thing is its based on lots of sources to errors - one of them is eyeballling the crank notch...

I think I will go for the 2 numbers but what will you do?

Thanks

Any of the numbers will work, the trick is getting the second cam close to the first..Thats where you fudge at the crank and centerline.
Bruce

The cams are slightly advanced. To retard slightly, jump the timing chain at each cam one tooth right to left. Net, the sprockets rotated CW. Retime the cams, the pin will need to fit into a different hole. The new setting will be closer to 3.15mm.
If you jump the wrong direction, the new setting will be closer to 3.19mm.
Some folks prefer to set the cams slightly advanced to accomodate chain wear.
By jumping the chain at the cam sprocket one tooth at a time, you can get the timing exactly to spec.
This is not intuitive, but it is part of the Porsche design.