Jon,
I have a couple Norton motorcycles that necessitated my buying Whitworth tools.
A 7/16" AF wrench is a tight fit on a 3/16 Whit bolt or nut. A 1/4 Whit is halfway between 1/2" and 9/16" if I recall correctly. I'm not really sure because I memorized which bolts on my Nortons I use the 1/4" Whitworth wrench on a long time ago. That's because 1/4 Whit (5/16" BSF) is the size that I've found I really can't substitute an SAE wrench for.
If you want a list of suggested vintage British motorcycle parts vendors contact me off the list and I'll send it to you, pretty much any of them will have these tools.
Eric Goforth Durham, NC USA
Jon Brownell wrote:
> I bought a vintage set on ebay for a modest amount.
> There are a bunch on there at the moment.
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> JB
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> Jon Brownell
> Mill Valley, CA, USA