Here is a graphic that shows the preferred tightening sequence and required torque for the cylinder head on a 750 or 850 Norton Commando.
It is worth noting that actually the bolt head sizes were whitworth only right the way through production.
The official spanner size for the ones marked 7 and 8 on my drawing is actually 3/16“ WW and remained so right up until the end of the MK3 Commando production.
However, it’s a really sloppy fit, and the 7/16” AF as marked on my diagram is a much better fit.
Of course through Dommie and Atlas production, then into Commando builds up until 1973, these were 1/4” WW (as mentioned in the note on the drawing).
Norton very sensibly then saw fit to slim down the head size to ease access.
This is also available as a PDF download in case you want to print it out to keep handy in your workshop!
Just click here to download
This article is from a series of Handy Workshop Guides I have put together.
These may be of interest to you: