Attributes . the thinner the diameter of the needle, the more fuel will be drawn. The thicker the diameter of the needle, the less fuel can be drawn. 10mm - 2.505. 20mm - 2.505. 30mm - 2.505. 40mm - 2.376. 50mm - 2.040. 60mm - 1.606. 30-38 Spigot Mount . Names