<html><body>When the British auto industry was switching over from BSF/W to UNF the explanation was published in the Austin Service Journal Volume 24. This is a good description of the differences.<div>Also this chart has some very good measurements of the various hardware.</div><div><br></div><div>Nice Christmas cards of Healeys in the snow...I don't have any snow, or my car out in the weather-it would be rain here in the Northwest. Here is one of the sister car to Michael's at our local car show-last year...none this year ...or next? Season's Best...stay safe! Hank<br><br><div class="reply-new-signature"></div><p>-----------------------------------------</p>From: "Harold Manifold" <manifold@telus.net><br>To: "Michael Salter", "Bob Haskell"<br>Cc: "Healey List"<br>Sent: Wednesday December 23 2020 6:39:51PM<br>Subject: Re: [Healeys] Whitworth vs UNC<br><br>
<div dir="ltr" align="left"><span class="314203502-24122020"><font color="#0000FF" size="2" face="Arial">Understanding UNC and Whitworth is one thing but BSPP and
BSTP fittings is a whole 'nother rabbit hole!</font></span></div>
<br><div lang="en-us" class="OutlookMessageHeader" dir="ltr" align="left">
<hr><font size="2" face="Tahoma"><b>From:</b> Healeys
[mailto:healeys-bounces@autox.team.net] <b>On Behalf Of</b> Michael
Salter<br><b>Sent:</b> Wednesday, December 23, 2020 9:48 AM<br><b>To:</b> Bob Haskell<br><b>Cc:</b> Healey List<br><b>Subject:</b> Re: [Healeys] Whitworth vs UNC<br></font><br></div>
<div>Thanks Bob ... I think you have nailed it.
<div><br></div>
<div>M</div>
</div>
<br><div class="gmail_quote">
<div class="gmail_attr" dir="ltr">On Wed., Dec. 23, 2020, 12:46
p.m. Bob Haskell, <<a>rchaskell@earthlink.net</a>>
wrote:<br></div>
<blockquote class="gmail_quote" style="padding-left:1ex;border-left:#ccc 1px solid;margin:0px 0px 0px .8ex;">
Michael,<br><br>
I'm going to guess 1/4" BSP. 0.518" OD - 19TPI.<br><br><a href="https://britishfasteners.com/threads-bsp"></a><a href="https://britishfasteners.com/threads-bsp">https://britishfasteners.com/threads-bsp</a><br><br>
Cheers,<br><br>
Bob Haskell<br>
Austin Healey 3000 BN7/BT7 registrar<br><br>
On 12/23/20 11:30 AM, Michael Salter wrote:<br>
> Well I have one for you Curt.<br>
> The thread on the oil drain back pipe on the 100 engine
(1B1236) has<br>
> me stumped.<br>
> The tube is 0.500" O.D. with an I.D. of 0.362"<br>
> The OD of the thread is 0.511" and it is 19 T.P.I.<br>
> I cannot find a 19 TPI x 1/2" pipe or tube spec anywhere ....
any ideas?<br>
><br>
> M<br>
><br>
><br>
> On Wed, Dec 23, 2020 at 10:54 AM Curtis Arndt <<a>cnaarndt@gmail.com</a><br>
> <mailto:<a>cnaarndt@gmail.com</a>>>
wrote:<br>
><br>
> Here is an excerpt from one of my
articles..<br>
><br>
> On Tue, Dec 22, 2020 at 1:48 PM Curtis
Arndt <<a>cnaarndt@gmail.com</a><br>
> <mailto:<a>cnaarndt@gmail.com</a>>> wrote:<br>
><br>
> The bolt is 5/16" BSW!
Don't let anyone tell you different.<br>
><br>
> Even my 45K original mile '60
Bugeye has its original 5/16"<br>
> BSW bolt in the generator
front plate. The problem arises<br>
> since a 5/16" UNC bolt has
the same tpi (threads per inch) as<br>
> the 5/16" BSW bolt. The
issue is that UNC has a thread pitch<br>
> angle of 60° and
Whitworth by definition is 55°. The wrong<br>
> bolt will never torque
properly and will eventually wear the<br>
> aluminum generator front
plate.<br>
><br>
> Cheers,<br>
><br>
> Curt<br>
><br>
> On Mon, Dec 21, 2020 at 3:53
PM Roger Grace<br>
> <<a>roggrace@telus.net</a> <mailto:<a>roggrace@telus.net</a>>> wrote:<br>
><br>
> My
understanding is that they are close but not<br>
> interchangeable
?<br>
> Thread angles
are slightly different.<br>
><br>
> For AH
generator adjusting link is this 5/16 W or 5/16 UNC ?<br>
><br>
> At back of my
mind think they should be Whitworth - think<br>
> you told me
that is why they come loose if you use UNC ?<br>
><br>
> Finding it
difficult to identify one from the other.<br>
> Any tips to do
this welcome.<br>
> Have a definite
W bolt and comparing to UNC can only see<br>
> slight rounding
of UNC ?<br>
><br>
> Moss sent me a
UNC bolt for this link - well that is what<br>
> they called it
?<br>
><br>
> Would
appreciate your expert input.<br>
><br>
> Regards,<br>
> Roger Grace<br>
><br>
><br>
>
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