Joined: Nov 2016
For a 289, I'd go with a 4100 (if you just happened to have one, or knew someone who had one with the 1.08 venturi). If it's a really hot 289, you could use one with the bigger 1.12's. Unfortunately, 4100's are getting pretty scarce these days.
The Summit M-series carbs are a direct descendant of the 4100s, and have some really nice features. They are easier to tune, and even look a lot like the Autolites. For a mild build, I'd get the 500 CFM version. If you intend to upgrade heads, cam, intake, and exhaust, you could use the 600 CFM version easily. These carbs also happen to be cheap, but despite their $300 price tag, they offer features you don't start to see on other carbs till around $600 or more.
Both the 4100 and M-series carbs use annular boosters. "So what? How does this help me?" you may ask. Well, for any street driven car, good fuel atomization is the name of the game. Unlike other booster types, annular boosters deliver a very fine spray of fuel, and do so with very little signal (pulses from the intake). Since liquid gasoline does not burn, only the vapors, this means that a lot less gasoline goes out the tailpipe, and more of it is burned. For economy, power, throttle response, and general simplicity, both the 4100 and the Summit carbs are truly excellent. They even do well for most performance engines.
For extreme power production, (think professional drag racing) annular boosters are not typically used. This is because when gasoline is so finely atomized it becomes nothing but vapor in the intake, it takes up more room than liquid droplets. This can displace some of the oxygen. For a car that does not care about economy at all, a Holley with cheap downleg boosters can probably deliver a few percent more peak horsepower at wide open throttle, if it's tuned to take advantage.
However, in all other driving conditions - like part throttle, cruise, and, well, every other situation, where your car literally spends 99% of its life as a street car - the annular boosters are superior. Your car will have more average power, and far better economy. I am not just speaking from theory, books, and what I learned on the internet, I've experienced this and proven it to be true on my own car. I foolishly 'upgraded' my car from a 4100 to a Holley 600 carb when I was a kid, and frankly, there was no comparison.
Hope this helps! =)
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