My son & I have just gotten a 1974 Duster with the 225. The Carb is pretty gunked up, but we got the coil spring thermostat working but the lean idle is bad. The car runs great at 40 mph. When you put the pedal to the floor from a stop it dies, if you hit it while at speed it misses.
We ordered a re-manufactured from Rock Auto that should be here soon.
We are both novices but we found a Haynes manual (dart & swinger 67-74) that has treated us well so far. I've read the article on the 1920 carb on this sight too.
The carb comes with choke pull off so that leaves just one vacuum line,
What do we need to be ready for when we do the job? We are planning on 7 hours on a Saturday.
Hoping to mine the collective wisdom of this group for tips.

Do not send the old carb as a core! Whatever comes as a "reman" carb is a lottery. Rebuild the old carb yourself. It is a 1920, not too colplicated.

Just basic stuff: did you check the fuel level in the carb bowl is right?

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/6 Dodge Charger 69
...there's nothing like using the "Search" link above to solve most of your problems...

Umhh, one vacuum line... In the old carb, or the new one? Your car is a 1974, you should have many vacuum ports in the carb (advance, pcv, egr, charcoal canister, thermostatic air filter... It does not look like the original application.

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/6 Dodge Charger 69
...there's nothing like using the "Search" link above to solve most of your problems...

Not a 1920, it's a 1945 on a '74. The early 1945s ('74 was the first year) are problematic, but "remanufactured" carbs are garbage. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. Tune-up parts and technique suggestions in this thread. The Haynes manual will lead you astray; you'll want to get the three books described in this thread as quickly as you can.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan's spot on, 1974 was the first year for the Holley 1945, and it worked OK as the replacement to the Holley 1920. Dan's books and links are great to review before diving in. The Holley 1945 isn't a difficult carb to rebuild once you have reviewed the procedure and know that needs to be done. As pointed out reman carb are a lottery game, with the odds being not in your favor on getting a good one. The 1974 configuration used a fairly lean main jet in the carb, so while rebuilding if you want to upgrade it from a #58 to a #59 or #60 you can buy them easily from a speed shop or order over the counter at most auto parts stores, it uses the same jets as the Holley 2 and 4 barrel jets (but you may have to buy a 'pair').

Good luck.

The carb body on the car is marked 1920 near the manifold. Perhaps more investigating is order.
Thanks for helping us out.