I'll throw my 2 cents in since I've owned, driven, built and tuned Volvos with SU's and Webers. Comparatively the Weber will not offer quite the performance and mpg's of a nice set of SU's but will perform well enough to satisfy 99 percent of drivers. It should start easily, drive smoothly, accelerate when asked to, etc. The question is--Is the Weber properly jetted for your motor (did the jet sizes get recorded when disassembled?)? Accelerator pump working? Water heated manifold hooked up? Most (if not all) Weber kits lack a warm air provision which can be very important in cooler climates. Manual or auto choke? The auto chokes often need a bit of reengineering and fiddling. As others have already pointed out--none of this makes any difference if other systems (ignition and mechanical condition of the motor) are not up to snuff. Do check your ignition system for proper advance, etc. Do check compression and camshaft condition, etc. -- Dave