Even more excruciating detail:
The 3/8" NPT pipe thread has 18 threads/inch, and the BSPT thread
has 19 threads/inch. You wouldn't want to get those mixed up!
If you did, there would be a lot of obvious damage.
I carefully measured my old plug (which always fit fine), and it
was definitely 18 threads/inch. Sort of funny that Triumph
used an American instead of British pipe thread...
Doug Braun
'72 Spit
At 04:44 PM 4/13/2006 -0700, Doug Braun wrote:
>Well, I found out totally by accident that
>there are different type of tapered pipe threads,
>NPT, and BSPT. To quote some Web site:
>
>British taper pipe threads (BSPT) and American pipe
>threads (NPT/NPTF) have some similarities and some
>differences, but there are two sizes, 3 /4, that are
>difficult to distinguish with the naked eye. The two
>have the same nominal size and pitch, and sometimes
>can be differentiated only through deductive
>reasoning.
>
>So I probably used the wrong type of oil plug.
>In its size, the American and British pipe threads
>have the same diameter and thread pitch, so the
>difference must be in something more subtle liek
>the angle of the threads.
>
>Anyway, before I change the oil again, I'll get
>a genuine British plug. I good industrial
>supply house like McMaster sells both NPT and BSPT
>fittings. But since I change the oil once a year,
>I'm not going to worry about it right away...
>
>Doug Braun
>'72 Spit
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