Javelin And Jupiter Cylinder Head Nuts

[Mike Allfrey]

Until recently, I had a good supply of substitute cylinder head nuts, Part Number not shown (strange for such an important item to be missing from the Javelin/Jupiter List Of Spare Parts), but my understanding is that thicker nuts were used on later engines. Here in Melbourne there used to be a company until recently called BSF Bolts Pty. Ltd., that was allied to the aircraft repair industry. I used to get 3/8" BSF nuts, a bit thicker and slimmed down so that a 1/4" Whitworth socket would be used for tightening or loosening them - all in the interest of weight saving, but ideal for our use. These nuts were black-finished and featured good thread fitting.

My supply has dried up, and I am wondering if anyone knows of a supplier in England?

These aircraft engine nuts have worked well for me, and I think they should be investigated.

Regards,

Mike Allfrey.

[AmilcarJohn]

Dear Mike

I'm not sure I am familiar with the type of nut you are using. However, here are some well known UK suppliers.

Namrick are popular with the vintage car community in the UK:

https://www.namrick.co.uk/acatalog/Home ... ts__1.html

For aircraft-quality (at a price) you can try LAS:

https://www.lasaero.com/products/article/X03A5OVA3


I hope this is some help....

[Mike Allfrey]

Thanks John,

I will 'contact us' at the two Websites you have provided, giving them accurate dimensions. Something may come out of it.

I was sort of thinking 9 cylinder radial engines!

Cheers,

Mike A.

[Keith Clements]

In addition for those less conversant with threads, nut sizes, grades of steel and tensile strengths this page has some useful data.
https://www.fastenerdata.co.uk/fastener-grades

As we know the torque on the head bolts is a max of 35 lbs-ft so knowing the cross sectional area of your stud you could work out the desired grade.
Namrick nuts are British Grade R approximately equivalent to Din 6.8

For the head studs I use the standard size but with a 3/8 drive socket which has a narrower wall. I also use the extended nuts which are twice the height of full nuts on the bottom four studs. Extra weight I know!

Beware there are some suppliers who have inferior grade nuts and bolts not suitable for the high tensile world of cars. The zinc plated ones fall into this category which should be OK for some applications but not head or suspension components for instance.

[Nick Webster]

There is also, thanks to the likes of Ebay and similar, an increasing and easy availability of stainless steel nuts and bolts. Some outlets sell BSF / Whit sizes. It concerns me to hear of classic car owners who are opting to use them in the mistaken belief that all stainless steel is better than mild steel. While stainless may have certain advantages it has other drawbacks such as a thread galling when over-tightened and crucially, except in certain rarer grades they are not high tensile.

Nick Webster

[Forumadmin]

Stainless steel A2-70 grade is 700 n/mm2 which is weaker than Grade R 50 t/ in2 or 770 n/mm2
There is also A2 -80 which has tensile strength 800 n/mm2

[Keith Clements]

http://www.roymech.co.uk/Useful_Tables/ ... Calcs.html
https://www.engineersedge.com/fastener_ ... s_area.htm
https://www.clevtec.com/upload/Links/Te ... hreads.pdf
https://www.engineeringtoolbox.com/bolt ... _2065.html
to do the maths.
3/8 bolt diameter= 0.009525 m =d
Cross section 3/8 bsf 0.0839 in2 = 0.0839 x 645.16 mm2= 54.12mm2
35 lb .ft = 35/0.73756 N.m = 47.45 Nm = T required
Grade R = 50 T /in2 = 112000 lbs/in2 = 772.21 N/mm2
Max force = 772.21 N/mm2 x 54.12mm2 = 41688 N = F

KFd=T where K = .2 for dry or .18 for lubricated
.18x41688x 0.009525 =71 Nm which is max torque that could be applied to 3/8 Grade R bolt
so 47 Nm is well within bolt strength but not the average Jowett crankcase.

[Mike Allfrey]

Thanks All,

The nuts that I have been using locally are as follows:
Dimension Across Flats: 0.523"
Depth (Thickness): 0.511"
Material: Blackened steel. Grade: Not known.

I note that in By Jupiter, arrived yesterday, there is comment about coolant seepage at the cylinder head studs and the requirement for snug fitting plain washers on the studs. These are what I call 'close tolerance washers' i.e. absolutely flat and no plating of any kind. I think the JCC of Australia purchased a good quantity from England (JCS?) and I have always used them. The plain (not flat) washers that we get here now are all Chinese made, are very loose fitting and, to me are worse than useless. None of the local hardware suppliers have a clue as to what close tolerance washers are!

Back to the nuts. I did manage to buy a good quantity of 3/8" BSF plain nuts, but I wonder about their quality; also, they are not as thick as the later Jowett specified cylinder head nuts. At the lasaero Website I have spotted some 3/8" BSF nuts that are of bi-hex type and incorporate a decent looking flange to contact the plain washer. Having seen such nuts in SAE and metric forms, I noted that they featured a countersunk lead-in for the thread. I wonder if such nuts would be suitable for our use?

I will have nothing to do with an engine that has severely mutilated cylinder head nuts (and others) that have been subjected to incorrect spanner/socket size abuse. Hence my purchase of the nuts detailed above, but, as happens, I have run out of stock and the premises where I bought them is no longer there.

This whole hardware business needs a heap of attention, but with older car enthusiasts desperately trying to find the cheapest possible hardware for their Jowetts, Rovers and Lancias, the education is going to be difficult. A friend is restoring a Lancia Lamda (1920s), and his 'expert' engine man has managed to shear a few cylinder head studs. The problem? The studs are 9mm dia., and it seems that only Ferrari currently use that size hardware these days! What a chance for the artful bodger to be let loose, yet again.

To Keith - I had a set of Britool 3/8" drive Whitworth sockets, They were stolen during shipment of our Jupiter to Melbourne. I tried to find a new set here but local suppliers did not understand what I needed. In a number of ways, 1/2" square drive is too clumsy. Aldi, incredibly, had some 3/8" BSW socket sets on sale, I was tempted, but soon heard that the sockets are loose on hardware and do split.

I will investigate the bi-hex flanged nuts further and advise what develops.

Cheers, Mike A.

[Forumadmin]

I spent time at the Resto show on Sunday researching Whit/BSF tools.
Amazingly the choice is getting better. King Dick do a lovely set of ring/ open ratchet wrenches. Not cheap but very strong. I have had a set of their open enders that my father got me when I was a teenager. They have been in my toolbox ever since - little wear except for the smallest which was superceeded and no breakage..unlike many other makes made of poor quality steels.

[Forumadmin]

https://www.abbotstools.co.uk/9-piece-3 ... rth&page=3
https://www.abbotstools.co.uk/King-Dick ... rth&page=3

Cheaper if bought singly.


https://www.abbotstools.co.uk/King-Dick ... rth&page=2

[AmilcarJohn]

Agree about the King Dick BSF/BSW ratchet spanners. I couldn't justify the cost of a set, but bought the three most common sizes, which cover 90% of my needs.