Navigator Cylinder Head Nuts

Hi Nick, 

Your Navigator should have 12 nuts holding the cylinder head and if the correct nuts this is the spanner size. 

3/16 Whitworth. 

I use a box spanner, short, with 1/4W at one end, 3/16W at the other. Useful to carry in toolkit. 

Or others use a 3/8 drive and socket and various wobble bars and joints to avoid frame tubes. 

Maybe Cromwell tools? 

Peter

The trouble with box spanners, and this means ALL such, is they are soft, soon wear and therefore the torque you put through them is VERY variable. Parts that are less important and awkward need to respond to a box-yes.
Of course if you save a box for the head bolts, there is always the temptation to 'use it else where'
Yes a decent thin wall Whit socket is needed.

... I posted a pic of my arrangement using 3/8" drive Whit socket, a short wobbly extension and a longer non-wobbly one here somewhere. It's in this thread.

... are mostly from others!