If it's done absolutely correctly, a 2-carb setup works pretty well- - - -if, and only if carbs with about 2/3 of the volumetric capacity of the original single carb are used, and perfectly matched. Carter carbs for a 216 fitted to a 235 dual-carb manifold will run just about as good as the original single carb, and there's a possibility the top-end performance might be a little better. Everywhere else, the original single carb will outperform the duals. If you do enough internal modifications including a bigger bore, longer stroke, bigger valves, very radical camshaft grind, and lots of porting and polishing, plus a low-restriction TUNED dual exhaust, you'll get a very good-running engine at full throttle that will fall flat on its face everywhere else.
Bottom line- - - -there's no free lunch. If you're willing to lose practically all of the engine's low speed and midrange torque to get a horsepower gain at high RPM, go for the multi-carb setup and live with the bottom end losses. You'll spend several thousand dollars putting a high-speed-only engine together that will run like crap at any legal highway speed. Otherwise, put a single Carter carb on it properly calibrated for a 235, and be happy with what you've got.
Jerry
