A wee bit more about carburetors (or as the English spell it carburator (actually they have a few other ways too)
The simple carburetor actually they never were that simple and it was more the advent of clean air controls and the catalytic converter that rang the bell on carburetors. You just could not be precise enough in maintaining the proper air/fuel mixture at all times.
You see your carburetor had grown from the simplistic updraft carbs and early "wick" carbs (the first carb was built and used in 1882) to a carburetor that had 6 basic circuits. A cold start, hot start, idle, acceleration, high speed/full throttle and cruise - very often cruise was broke down into slow and fast so it can be argued that there are 7 not 6 circuits, regardless not so simple.
While the updraft carb had one great advantage, fuel droplets or flooding conditions did not happen to often (the fuel just ran out the bottom of the carb all over the hot exhaust but for some reason that did not seem to bother anyone too much) they were tremendously difficult to start in cold weather and relied completely on the power of the incoming air charge to get the fuel from the carb to the intake manifold. Not very efficient. Simple though.
By the 1930's or so most of the updrafts had been replaced with down drafts, which except for some noticeable expectations became the mainstay of fuel delivery. They work quite well and come in various "flavors" single, double and four barrel and could be found used in multiple configurations, a Ford flat head with three single barrel carbs on it; Pontiac GTO with three two barrels and Ford setting to giant 4 barrels on some of theirs!
Then there were the exceptions - side draft carburetors. The most known being SU, Zenith Stromberg & Weber. It has been argued that the SU carb was the best all around performance carburetor ever built. It would be hard to argue against that. Unlike their fixed jet downdraft brethren the side draft SU and Stromberg have a movable needle valve that moves as more air is drawn into the engine allowing the air/fuel mixture to be changing as the engine demands changed. It was still controlled ultimately by the size of the needle and jet used and various needles were available for each jet size. This allowed you to more closely match the carb to the true conditions it was being used in. The fixed needle and jet, as were most downdraft carbs. meant you pretty much lived with the mixtures you set up with needle and jet choice over a broader range than the variable would allow. You could richen the entire mixture a bit at idle but ultimately the fixed jet carb was just that, fixed.
Made it easier to adjust once you got the correct jets and needles and it has less moving parts so less problems over the course of its life. Also the side draft SU and all of the ones that copied it have no accelerator circuit - makes it much harder to start in the morning and can give a little more delay before coming onto the power band when you press down on your accelerator pedal.
But simple as they may seem as compared to the computer systems of today they needed to be right. Worn parts are a killer, throttle plates misaligned can ruin the performance. And just putting a bigger carb on can often rob you of power right where you want it. A larger bore will mean a larger volume of air entering the induction system but at a slower rate of speed so your low end power will suffer.
If you install a better flowing air filter onto your SU carbs you may actually have to install a leaner needle. Higher rate of air flow at the same throttle opening means the needle is out of its jet further, thus is richer at this rpm than it was. It may be to rich now.
Putting a super charger on sure does increase air flow and compresses the whole charge so we can add more fuel and get more power. We also increase engine temperatures and increase dramatically the forces in the combustion chamber (there was a reason that factory designed super charged cars ran at lower compression ratios) increased force can shorten engine bearing life big time.
It all needs to work correctly, correct style carb, correct size and jetting, correct induction - use a super or not, use a turbo or not - correct exhaust, to match what you are doing. If you increase the amount going in you better be able to put it out as fast as you are putting it in. Many times without rebuilding and redesigning your engine and exhaust system putting bigger carbs and induction systems on will send you backwards in the search of power.
While 1882 was a wee bit before I started playing with carbs I have worked, rebuilt, adjusted and setup most of them. And we still do today.
Give us a call or drop an email if you need yours rebuilt, setup or adjusted or if you are thinking of changing your induction system.