I fitted these Weber carbs to my 100D2 engine in 1985, to replace the leaking and worn standard Solex units. They were supplied by Chris Montague Carbs, set for Bristol engines. They bolted straight on using the standard Vokes air filter, fuel connections had to be modified. I recall there were some initial jetting problems and I got advice from Barrie Bird. Since then they have been fine. I still have the bill for the changed jets but unfortunately not the exact description. Barry may still be able to help.