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<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 tabIndex=-1>
<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></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 href="mailto:rchaskell@earthlink.net">rchaskell@earthlink.net</A>>
wrote:<BR></DIV>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex">Michael,<BR><BR>I'm
going to guess 1/4" BSP. 0.518" OD - 19TPI.<BR><BR><A
href="https://britishfasteners.com/threads-bsp" rel="noreferrer noreferrer"
target=_blank>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
href="mailto:cnaarndt@gmail.com" rel=noreferrer
target=_blank>cnaarndt@gmail.com</A> <BR>> <mailto:<A
href="mailto:cnaarndt@gmail.com" rel=noreferrer
target=_blank>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 href="mailto:cnaarndt@gmail.com" rel=noreferrer
target=_blank>cnaarndt@gmail.com</A><BR>> <mailto:<A
href="mailto:cnaarndt@gmail.com" rel=noreferrer
target=_blank>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
href="mailto:roggrace@telus.net" rel=noreferrer
target=_blank>roggrace@telus.net</A> <mailto:<A
href="mailto:roggrace@telus.net" rel=noreferrer
target=_blank>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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