Assuming the engine is a B230K and the carb is a Solex Cisac, "I am told" that the Weber 36/36 DCD will fit with only small modifications to the existing manifold. Sorry I can't be more specific; I had my Cisac successfully rebuilt by a professional, but next time it starts giving me headaches I will go the Weber route.
Good luck,
Erling.
http://radmannen.stavanger.kommune.n...myvolvo240.htm