I'm sorry but I can't believe that. I never had a venturi ever come loose in a
Weber carb in years of use. I think that is just some line someone told you
to get rid of you. If they are really loose there is usually a set screw that
is supposed to hold them in. Or they are a press fit and are not changeable.
Very unlikely to come loose. If you are referring to the booster venturis in
the center of the barrel. The gas comes through them and dumps straight down
the venturi. Don't see how it could come out the sides of that.

Maybe you have other issues like an intake gasket leak or a vacuum leak somewhere. You really should post some more symptoms. The BBer's may be able to help more. If you are having flooding problems. Have you set the float level?
Is the needle valve free to move without sticking? Are you using an aftermarket
fuel pump? Personally, I've found the aftermarket pumps run too high pressure
and cause flooding in carburated Volvos. I installed a Pierburg pump when I
encountered this and it was cured. I'm talking about the block mounted
mechanical pump. You can get your car to run correctly. But it does take some
tuning time and patience to make one change at a time. There used to be a
Weber supplier named Redline that carried everything. Try a web search for
them. Wish you well.
Dave 82 242ti