This is the shouldered hexagon blind nut that fits over the jet holder on the International and SOHC Manx timing covers (feeding oil to the BigEnd). It was fitted to all SOHC timing covers, but was also fitted on competition pre-Featherbed SOHC cambox bevel covers (i.e. those cambox's fitted with central oilfeed). The Featherbed SOHC cambox used a similar nut (our part no 0069), but was shallower to avoid hitting the top frame tube.
It should be noted that this nut was also fitted to OHV and SV models (as well as the SOHC models) pre-1936, where it had the part number 9013. However, approximately 1936-37 the OHV/SV models swopped this hexagon nut for a similar rounded blind nut with a screwdriver slot in it (part no 8750), which was then fitted to OHV/SV models until to the introduction of the plain timing cover in approximately 1938.
We will shortly be manufacturing the 8750 type - but believe that the type 9013 can still be fitted. If you wish to enquire on 8750 progress please email email@example.com
These nuts are CNC'd in stainless steel and look very pretty - and definitely improve the looks of either your SOHC or early OHV/SV timing side.