Classic Alfa Forums

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

Helpful guys at Eurocarb, Reading will advise you

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.

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.

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.