The correct size jet for the Amal carburetter is 140. The tapered needle should be in the second notch from the top although the position may vary on certain engines. Raising the needle tends to richen the mixture at high speeds while lowering the needle weakens the mixture. Slow running is controlled by the Pilot jet adjusting screw which is to be found screwed into the mixing chamber on the right hand side of the machine. As the type of carburetters has been altered considerably during the last 2 or 3 years we advise you to communicate with the makers concerned if further information is required. For further information re jet sizes, etc., for different fuels for racing purposes refer to pages 11 and 13.