i have a 223 that will have a header and a clifford 4bbl intake. i want to use a 2bbl carb and an adapter plate. what would be a good carb for the job? ive been looking at 2100s, autolites, and rochesters. what do yall think?
Some would call it blasphemy, but I think you can't hardly go wrong with a Rochester 2GC. Plentiful, cheap, dependable and efficient. About a billion in the junkyards that nobody wants. $15 kit and you're good to go for about 10 years....
its a totally stock 223. i dont know if it could handle a 4bbl in its current condition.
Actually that shouldn't be a problem so long as the 4 barrel carb is one of the usual vacuum secondary units that has been properly selected and set up and correctly tuned for your application. Keep in mind that the vast majority of the time the engine will only be using the smaller primaries when you're driving around town and generally speaking those are roughly comparable to a modest 2 barrel carb. It's only when you get on it pretty good and hard that the secondaries would open at all, and then only in response to demand.
One possible choice would be the same old Holley 390 CFM carb that so many folks use on their Ford 300's. You might need to make some tuning changes to it to get the best combination of performance and fuel economy, but Holley carbs are pretty common so tuning parts and expertise with them are fairly easy to come by.
On the other hand one of the garden variety 2 barrel carbs like any of the models others here have suggested could also work quite well, assuming it was properly tuned to work well with your particular engine. (Note that at least some amount of carb tuning and set up is likely to be needed no matter what kind of carb you use.)
One unorthodow suggestion I could toss into the mix would be a Quadra-Jet carb. (I can almost hear the shrieks of "BLASPHEMY!" as I write this. ) The Quadra-Jet carbs have the advantage of having very small primaries. That means that your engine could get fuel economy and low-end throttle response of the sort it would get when using a small two barrel carb, but would have plenty of 4 barrel "oomph" when you stomped on the gas because the secondaries would open as needed to increase the amount of air flowing into the engine.
As with any carb you'd need to get it tuned to work with your specific application, but that shouldn't be too difficult. Q-Jets may be less common than Holleys, but they still have a sizable following. Click HERE to see an article that discusses Quadra-Jet carbs. HERE'S a link to another article about them.
Any intakes that take the spread-bore and fit the 240-300?
All you need is a standard 4 barrel intake and an inexpensive adapter. The Clifford intake for the Ford 223 along with their standard 4 barrel adapter and a Quadra-Jet to Squarebore 4 barrel adapter will allow the Quadra-Jet to mount quite easily.
By the way, Quadra-Jets have a reputation for being able to operate properly at far more extreme angles than Holley carbs, which makes them a good choice for trucks that will be used offroad.
I found another useful link to a web page with a lot of links to web pages full of various kinds of info about Quadra-Jet carbs. Some of the links on the page have expired, but a lot of them do still work.
Also, you may recall that I mentioned that Quadra-Jet carbs have really small primaries, and I found an image that illustrates this fact pretty well. It's a picture of a stripped down throttle body plate from the bottom of a Quadra-Jet carb and you can really see how small the primaries are compared to the secondaries in this image. For reference, the two smaller round holes at the top are the primaries, and the two larger round holes directly below them and partially covered by the jaws of the vise are the secondaries. Here's the link to that image:
Would a 2bbl really be easier on fuel than a 1bbl or a 4bbl?
That depends on a lot of factors including the types of the intake manifolds used, the specific ways the carbs have been tuned, which carbs are used, etc.. There's no single correct answer to that question.