This is one of the New Weber Carbs 34/34 and works great when jetted properly for the CJ 258 and the Use of Holley low pres Fuel Regulator. I have helped a few dozen or so get this working much better and all webers work the same. It is not uncommon for a carb that fits Jeeps, Suziki's, and other vehicles to need proper jets. I have been working with the factory and they are starting to ship smaller jets like what I have suggested in my Weber Tune Link/Thread. It takes ten minutes to change all four jets and they cost $5-6 each. You can order with the correct jets or if you ask nicely Weber N. America might send you the smaller jets no charge. They have done this for many JeepForum members I have helped.
I have already done the searches, work, and play time. If you follow the suggestions in this link the Weber 34/34 or the 32/36 will run great. If you research other carbs they are recommending the same size jets I am, funny how that works out. 46-47-48mm jets seem to be the norm for 258.
Here is the Weber Tune Thread I wrote:
Just like any larger carb your ignition and overall health of engine needs to be good if you want the performance improvements.
As for this not a Weber Carb.. Come on think about this. It has Weber on the box and is shipped from one of several importers of Weber. It it was not a weber product there would be quite the lawsuite for using their name, the weber name. It is made by Solex under contract for Weber and is made in France. All multinationals use subcontractors and Weber and Solex are used on audi, porsh, BMW and many world famous cars as OEM and aftermarket. They work.
Order with or install the proper jets and you will be a happy camper. I replaced single barrel carb and intake/exhaust with a two barrel intake/borla header/Weber 34/34. Runs like new and the video is at the end of the Tune Thread for the proof.