www.EnfoStuff.com

Can anyone help me out here please, I have twin 40's on my Lotus motor and somehow one of the spindle nuts has worked loose and my linkage is loose. Anyone know what thread that nut would be, having a real job finding a nut to fit. Failing that, anyone got one the would be willing to part with? I'm guessing it would be metric, uses an 11mm wrench to remove it.

Weber uses metric hardware. I have metric nuts and bolts but not sure exactly the right one you need. These guys will know : http://www.piercemanifolds.com/Articles.asp?ID=160

Like Pete says, it's Metric. Don't forget the locking tab under the nut if you don't get a locking style nut and be very careful of the torque you apply to the nut, especially if it is an older Weber with a brass throttle shaft. These can twist very easily throwing off the balance between the two throttle plates.
If you get stuck you could order something like this from Ebay.

http://www.ebay.com/itm/2x-Nut-lock-was ... 1395099175

Thanks guys, appreciate your input and the links.