At 09:06 AM 1/14/2001 -0600, David Lieb wrote:
>Do you really expect me to believe that my MG has one metric bolt on it? I
find that a little hard to swallow.
I have been advised that these threads are British Standard Straight Pipe
Threads (thanks Ed), which according to Machinery's Handbook are based on
Whitworth Standard Threads, which in turn are based on Metric dimentions.
These plugs are indeed 13mm diameter, and possibly 19 threads per inch
(notice the mixed standards) rather than 1.25mm pitch (which would be
closer to 20 TPI). This is such an odd combination of diameter and pitch
that I can find no other thread standard that includes this size.
Here's a wild guess for an emergency repair though. You can buy from
domestic parts stores a slightly oversized 1/2-20 oil drain plug that is
intended to be used in place of a stripped out 1/2-20 thread in the oil
pan. These replacement plugs usually have at least one cutting flute
similar to the flutes on a thread tap, such that the new plug will form its
own mating thread on first installation. I believe this repair plug will
be at least 13mm in diameter, and maybe even a bit larger, so it will
likely work in the MG oil pan as well. But I would not recommend going
this route unless the thread in the pan is messed up to begin with.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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