Generally
1/4″UNC 18.6 mm below the skull 3/8″ Wrench socket
15 kr
Cheaper than the original
1/4″UNC 18.6 mm below the skull 3/8″ Wrench socket
Check that the screw is not too long and bottoms out, this screw is 3.2mm longer than the original. Cut it off if it is too long. Don't over tighten the screws so the valve cover gasket is pushed apart, just right is always best