T24 Carb problem

[David.H]

Thank you John

So I need to set the shut off needle valve to operate sooner, ie to have less fuel in the float chamber.
Naively if I put another washer under the valve seat, this should lower the needle & thus the level by the same amount (about a millimetre)...is that significant I wonder?
I know the "1.5" of the needle valve refers to the size of the intake (diameter?)
D