The best Carburetor

So if I clicked on this post I would immediately reply "it depends on what you have, what you want to do, and how much you want to spend" and****ume someone new to carbs that doesn't understand that's a loaded question would ask. But I'm asking the question and not new to carbs. So I'm going to set this question in one single parameter: What is the best Carburetor in terms of how well it stays within the range of the AFR you set it up for. Any kind of changes your engines makes that will constantly change the AFR: wide open throttle, Fast accelerations, fast shifts, outside temp changes, temp changes inside the engine bay, barometer changes, altitude changes, and even different fuels (when sometimes you put no ethanol and other times you don't).

This idea started when I dipped my toe in the aftermarket TBI injection (fitech). I'll spare the details but after much headache it made me really appreciate a carburetor. What it did allow me to do is keep an eye on the AFR reading of the Fitech and at the same time the AFR gauge on another car with the Edelbrock AVS2 carb. IF there was a difference in how quickly the AFR adapted to changes, I didn't notice it! Yes I know in theory a mechanical device is racing the speed of an electrical signal. But that electrical signal still has to get it's input from an O2 sensor from the exhaust.

My own observation and experience with carbs. That AVS2 was great! It has annular boosters which helps give a more precise mixture. I also can't help but think metering rods with theoretically infinite adjustments of an edelbrock is going to be much more precise than a metering block in something like a holley.

I also drove a suzuki samurai around for a while that had a Harley CV carb. I didn't have an AFR gauge on it but if I didn't tell you it wasn't EFI you wouldn't have known. It ran good at angles, elevation changes, bouncing around, or whatever else you threw at it. Yes that's kind of cheating because it's probably the one practical application for a CV carb on a car I'm aware of.

Finally I have yet to try it but I will soon be bolting up a motorcraft 2150 on a 77 bronco. Early broncos never had this carb just the very close relative: autolite 2100. The difference is the motorcraft I have chosen has a factory altitude compensation device on it. Basically just a barometer that opens a new air bypass to add more air when the air is thinner to keep it from flooding. It's also equipped with annular boosters and some of the last models even had metering rods they used to lean out the mix at idle. This is why I chose this carb. I have no experience actually running it but I expect good things!

So what am I missing? Anybody have any data on AFR of different carbs and EFI? Or knowledge of what carbs perform the best in terms of keeping the narrowest range of an AFR?

 

To me picking a carb depends first on if the particular carb is the right size for your engine. All of us old farts knew that guy in town that had a 750 Holley on his stock 283 or stock 289 with maybe a high rise but all too often and adapter who could never get it to run right and always got mad when you told him the carb was just too much for the engine.
Beyond correct size a reasonably common carb that you can get kits for at the local parts house or order "the good kits" from one of the "the good kit" carb kit vendors. That is pretty well HAMB friendly carbs with quadra jets thrown in to the mix.
Then you have to actually like that brand and style of carb. I ran Holleys for years end because for me they were easy to work on and I cold jet one to have it do exactly what I wanted it to do. My buddy used to give me ones he took off engines he got just because he didn't want to fool with them and a couple ended up in the bed of my truck and rode around for a couple of days before I found them.
On the other hand I get away equally well with Edelbrock or AFB carbs or Quadrajets and most two barrels.
What I don't suggest is goiong odd ball just for the sake of going odd ball. A guy I knew back years ago decided that he was going to make a manifold to bolt a set of 750 Honda carbs on a little 4 banger he had rather than buy and available intake and put the carb most guys wanting more power out of that engine ran. I moved before he got it going and never did hear if he got it going.

 

In this "What If" case of choosing the BEST, I would look at the people that have no rules, all the ability to test, tune and select (time + money) and have to run them for an extended time and varied conditions.
Drag is run a couple minutes at idle and WOT on a flat. Back to the pits and readjust.
NASCAR is varied speed and over time, but limited by rules (single 4). This is probably closer to real world USA rodders and cost. The top end Holley stuff is heavily researched and has a huge amount of adjustment and parts choices.
The top classes for endurance road racing or rally racing is probably closer to wide range extended use, and they tended toward Individual Runner (IR) multi carb stuff before FI took over. This applies to fewer cylinders and smaller displacement all the way up to the big block GT40s.
You gain from tuning the intake without worrying about balance, at the cost of complexity and possible problems with dirt leaning out one cylinder.
On the street, where flexibility (not having to constantly fiddle and tune) and cost are larger concerns, the single carb is going to be the common choice. Choosing between the different types will mostly come down to experience and availability. That time + money thing means most people do not have the ability to try out a half dozen carbs, get proficient with each and be able to select without bias. That's why it's often suggested to ask someone who has that experience to help with the selection, just like picking a cam.

Given that typically you go out, buy the carb and might even get the tuning kit too, bolt it on, hook things up, then do some adjusting, the main thing is easy servicing and holding that setup. A step above is wide band tuning. A step above that is dyno tuning. Given the wide range of engines, carbs, usage and effort, there is also a wide range of BEST.