Cylinder head nut

I presume you have the right nut. Longer than the front nut.

Whats needed is a very special one that works!

... a thin walled cranked Gordon (I think) ring spanner in 2 so that I had 2 short ones - the 5/16" end was ideal for this job and still comes in useful when I need to get at an inaccessible nut / bolt. If I get around to it I'll post a pic....

A reasonably slim open ended spanner has always worked for me. There isn't much swing avaliable, so you might have turn the spanner over each time you wind the nut another half flat. At least it's more likely to be oily rather than rusty.

Alternatives..........a reduced hex nut with a washer. On my engine the rear nut is 5/16th.

King Dick spanners are very thin and do not need grinding to fit betwen the fines. Bedford or Gordon ring spanners have quite thin but very strong shoulders.

Could probably use a front sleeve nut cut down a lttle and drilled out then re-threaded 3/8ths??

Shouldn't the nut be one of the double height ones? So long since I did it, I can't remember exactly. 

.. my modfied one is a King Dick. Picture attached,

The higher rear head nut, # 24250 also called 06.7870 as well as the earlier E3224 also called D12/979  half width nut  is available from the usual vendors.

hello now Phills right you need to go to a 5/16 reduced hex nut and I made my own spanner to fit out of a jembro 5/16s and 1/4 at there other end jembro spanners are thin so you grind a bit more off both sides to make them even and grind the round side down so it will fit right and you can then get about a half turn and I have about a dozen jembro spanners along with bluepoint and william superslim   and four Bedfords  And just one king dick  and the odd BSA spanners  As I restored Many Bsa C15s and B40s  only had one A10 it was a Road rocket from 1955  I paid fifteen quid for it off a farmer Mr jackin  I worked for in the potato harvesting time and had to push it home with old potato sacks over it,  and that would be october 1968   why that another story,   yours  anna j   

RGM offer a combination spanner for use on these nuts and useful box spanners for cylinder head and sump and forks. Worth a look on their website.

Back in the day (55 years ago!) I bought a special short box spanner for that bolt.  I think it was a Norton part and certainly would have bought it from my local Norton dealers - Alec Bennett or  Lawton & Wilson.  I still have it somewhere, but I suspect the rust gremlins may have weakened it!  So a cut down box spanner with a new tommy-bar hole through it might be the best bet.

George

This one from Andover Norton should also do the trick https://andover-norton.co.uk/en/shop-details/18702/combination-spanner-1-4-ww-obstruction-.

Some of the vintage tool sites sometimes have crescent/half-moon shaped ring spanners in imperial sizes at reasonable cost.

I have heard you can heat up and bend an ordinary 1/4W ring spanner but I have no personal experience of this.

Andy

George, 

I have attached a photo of the spanner I use when fitting Dominator heads. It's a Heyco no 430 from Germany. It gives good clearance on the nut at the rear and good rotation so the nut tightens quickly. It's in Whitworth format so fits properly.