Carburetor Float Needle and Seat Washer

[Jim S]

I have a 1957 A7 with a 376 carburetor. I just installed a new float needle and seat adapter, however I'm not sure if I should install a fibre washer under the seat adapter. The Amal site shows a fibre washer but says "If fitted". Draganfly says to install a washer if a Teflon tipped needle is installed. I have another document showing an exploded view of the carburetor and no washer is shown.
If a washer is installed, I expect that the fuel level in the float chamber would increase by the thickness of the washer.
How do I determine if I need this washer?

[JulianS]

If the carb uses the thick O ring and no recess in the body below the float needle seat then no washer. Use a washer here and the result will probably be flooding  and the float may rest on the tickler and prevent the needle from properly seating

If the carb uses a thin O ring and has a slight recess in the body below the float needle seat then it needs a fibre washer.

Photo shows body with recess.

[Jim S]

Thanks Julian
I have no recess, so no washer.
However, where is this thin/thick o-ring?

[Editor]

I think Julian is referring to the Air Seal on the outlet flange. The Burlen ones use the same O ring as the concentric. (Thinner).
I've been caught out by fitting a washer until I realise there shouldn't be one. After a bit of logical thinking, I realised the fitting is above the fuel level in the float chamber so you don't need one there under normal running and the amount of fuel likely to weep from there upon tickling is minimal.