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Re: [Spridgets] Thread about Threads Re: Fuel line question

To: WeslakeMonza1330@aol.com
Subject: Re: [Spridgets] Thread about Threads Re: Fuel line question
From: "Curt/Nancy Arndt" <cnaarndt@gmail.com>
Date: Sun, 11 Sep 2011 17:05:18 -0700
Spridgetiers

On Sun, Sep 11, 2011 at 4:04 PM, <WeslakeMonza1330@aol.com> wrote:
*<I don't believe BSP threads are the same as Whitworth threads though I've
not checked.*>

With all due respect, here is a short primer on British thread forms...

For those who aren't familiar, *by definition*, Whitworth thread forms are
those where the angle of the threads is 550 versus the 600 of most modern
threads.  Therefore the five major *Whitworth Thread Forms* include...

*British Standard Whitworth (BSW)* - On the Bugeyes, at least, you'll find
that the 5/16 X 18TPI bolt on the lower front generator bracket is this
thread form.  (This is somewhat interchangeable with UNC or SAE Coarse which
is also 18 TPI and will thread into the hole in the front generator
bracket.)
*British Standard Fine (BSF)* - Most engine, transmission & suspension bolts
on Austin Healey 100s.
*British Standard Pipe Parallel (BSP)* *or (BSPP) *- Brass drain plugs and
valves, fuel and brake line fittings on most Healeys.
*British Standard Pipe Tapered (BSPT)* - As above but tapered, not used to
my knowledge on Healeys.
*British Standard Brass (BSB)* - Used in thin walled tubing and ALL have
26TPI no matter the diameter.  The mounting post on Lucas SFT/SLT 576
driving lights would have been this thread form.

Other threads (obscure if not obsolete) that used the Whitworth 550 angle
include, British Standard Conduit (BSCon), Model Engineers (ME), and British
Standard Copper (BSCopper).

Other British Fasteners that are *NOT Whitworth* include...

*British Association (BA)* - Used in Healey instruments and fuel pumps.  47
1/20 angle of the threads.
*British Standard Cycle (BSC)* - Used on a lot of British motorcycles and
most but NOT ALL threads are 26 TPI.  The angle of the threads is 600.
Wikipedia lists BSC as Whitworth and they are WRONG.
*Cycle engineers Institute (CEI)* - Older cycle thread superseded by BSC.
The angle of the threads is 600.

The following two thread forms are what the British switched to after moving
from the Whitworth standard.  These are the majority of the fasteners used
on Spridgets.

*Unified Coarse (UNC)* - Identical to American SAE Coarse and essentially *
Interchangeable*.  The angle of the threads is 60 degrees.
*Unified Fine (UNF)* - Identical to American SAE Fine and essentially *
Interchangeable*.  The angle of the threads is 60 degrees.

Cheers,

Curt


On Sun, Sep 11, 2011 at 4:04 PM, <WeslakeMonza1330@aol.com> wrote:

> **
>  Yes and no or maybe. British cars do have some BSP and BST - British
> Standard Taper or is it BSPT?  However, I don't believe BSP threads are the
> same as Whitworth threads though I've not checked.  I think you'll find the
> early steering rack, which originated on the Morris Minor has Whitworth
> fittings.  Maybe the dampers have Whitworth threads - Peter C will know,
> probably all this stuff is in a book when it ought to be in my head but
it's
> late.......
>
> Weslake-Monza 1330 - Monday and I should be in bed!
>
>
> In a message dated 11/09/2011 02:35:20 GMT Daylight Time,
> cnaarndt@gmail.com writes:
>
> Most pipe threads on British cars of this vintage are Whitworth threads,
> British Standard Pipe (Parallel) to be specific.
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