Idle screw O ring

[Faffmeister]

Have looked at various diagrams etc and am unclear with Idle screw should have one or two O rings fitted

Existing screw has O ring in groove adjacent to head. Should there be one at needle end?
1500 engine with twin 36idfs

[alfadave]

Helpful guys at Eurocarb, Reading will advise you

[Sprint88qv]

Haynes manual for Weber carbs shows one o ring only and it looks to be below the spring as the Dellorto DRLA has it. But agree, check with Eurocarb guys.

[justsuds]

I've just checked on a couple of Webers that I have here on an engine, - there is one o ring on each of the idle screws.
Cheers, John.

[KevJTD]

Pretty sure there won't be an O ring at the needle end, that's where the air bleeds through so it will simply fit into a tapered insert so as you wind the screw in and out it lets more or less air through, if there was an O ring at the bottom that wouldn't work well.
The O ring at the top is there to stop the air leaking out through the threads.