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Head Nuts ...Help!!
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whiteshadow



Joined: 24 Jan 2011
Posts: 78

PostPosted: Thu May 17, 2018 2:36 pm    Post subject: Head Nuts ...Help!! Reply with quote

I've been having a horrible time trying to keep my head gasket tight and sealed (with a trip coming up!). After much discussion with the club, I've brought new high tensile studs etc.

The one thing I just cannot seem to find is high tensile 3/8 BSF nuts!!

After being lost in the internet for hours, I have only found one supplier who claims that their 3/8 bsf nuts are 8.8 steel. When I looked at them they seem fairly poorly formed, so I decided to test them on a properly stamped high ten. bolt. Both this and a 'cheese' grade nut just kept on tuning about 30-40 ftlb.

Am I missing something??....I'm beginning to think that this must be the cause of my woes, but where can I get suitable nuts for the head studs as I hadnít yet found a car that uses the same thread.

Any help would be appreciated


Regards
M
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Kleftiwallah



Joined: 27 Oct 2016
Posts: 222
Location: North Wiltshire

PostPosted: Thu May 17, 2018 6:48 pm    Post subject: Reply with quote

I've found "Peter Rabbit" to be a good source of weird stuff!

Cheers, Tony.

http://www.peterabbott.co.uk/contact-us/
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It may work in practice, but not necessarily in theory!
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47Jag



Joined: 26 Jun 2008
Posts: 1468
Location: Bothwell, Scotland

PostPosted: Thu May 17, 2018 7:07 pm    Post subject: Reply with quote

Try Alan Gibbins at alan@ssjaguar.co.uk

Heís the SS Jaguar spares rep. These engine have BSF head studs, domed on the outside of the rocker cover and plain inside.

Art
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whiteshadow



Joined: 24 Jan 2011
Posts: 78

PostPosted: Fri May 18, 2018 8:31 am    Post subject: Head Nuts Reply with quote

Managed to find some which are grade R....think this as roughly 8.8 grade?...hopefully these are better formed.

Obviously bolts, tensile stregth and max torque is a hugely complex subject, but Iím beginning to suspect that the torque value of 35ftlb (47.5N) on a 3/8 fastner is far too close to the max torque!!?. Especially as i doubt they were using unicorn steel on this 1940 engine.....what do you think?
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ukdave2002



Joined: 23 Nov 2007
Posts: 3467
Location: South Cheshire

PostPosted: Fri May 18, 2018 11:57 am    Post subject: Reply with quote

If you know someone with a lathe you could purchase EN16T hex bar and make your own?

https://www.nogginend.com/product/EN16T-Hexagon-Bar

Dave
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colwyn500



Joined: 21 Oct 2012
Posts: 1740
Location: Nairn, Scotland

PostPosted: Sat May 19, 2018 9:24 pm    Post subject: Re: Head Nuts Reply with quote

whiteshadow wrote:


Obviously bolts, tensile stregth and max torque is a hugely complex subject, but Iím beginning to suspect that the torque value of 35ftlb (47.5N) on a 3/8 fastner is far too close to the max torque!!?....what do you think?


I had an Austin 10 and the Drivers' Club technical notes pointed out that back in the thirties there was no torque spec. on that car's head-nuts, So the recommendation was to tighten the nuts by "feel" using the appropriate ring-spanner. I found the best way was to use my full force whilst my hand was right in the middle of the spanner.
Because the thick copper gasket would settle, obviously you had to redo this after a short time and then again as time went by. The story went that by the time you had it sorted it would be ready for the head off for another decoke, Wink
3/8 head studs are not all that strong and can be easily stretched or pulled out.
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jp928



Joined: 07 Jun 2016
Posts: 247
Location: Australia

PostPosted: Sun May 20, 2018 6:38 am    Post subject: Reply with quote

Dont know about 3/8", but 8.8 M10 bolts have a recommended torque of 55Nm, 10.9 bolts are 75Nm. So the 47.5 is 15% under ...should be enough.
Have similar queries about head bolts on my Rover, recently rebuilt by A.N.Other.
jp 26 Rover 9
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