My 71 Dart (225, 1bbl Carter) starts fine and runs well for about the first 40-60 minutes or so but then has a tendency to stall and struggle to restart. When restarting, it cranks but doesn't turn over. Is this a symptom that my idle screws need tweaked? Can that affect the car starting or is this something else?

Percolation in the fuel line and/or carburetor. Do the fuel line mod , and make sure that you have the correct 3/8" thick carburetor insulator/gasket between the carb and the intake manifold. Also make sure the carburetor's float setting is correct. In doing so, you may as well go through the carb with a good quality rebuilding kit to ensure dirt and/or leaks aren't aggravating matters. Also make sure that you've got the correct PCV valve installed, with a good-sealing grommet and uncracked hose, and see that the crankcase breather (canister at the top rear of the valve cover) is internally clean—if in doubt, get a new one.

And yes, the idle mixture needs to be set correctly, though that's your last step, not the first. See this post for instructions.

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Thanks Dan. I meant to mention that I done the fuel line mod.

I did notice what looks like a bit of leaked gas on the intake manifold after I got it home. Is a sign of something wrong with the float bowl? Are there directions for setting the float bowl? I searched around but didn't find a basic 1-2-3 walkthrough.

Thanks!

First step, read and follow the instructions in this post.

And yes, dripped/leaked gasoline on the manifold means you should clean out the carburetor and check the float adjustment.

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

Might want to check and make sure the throttle shaft is not worn out. I've seen them get so worn that the vacuum leak they cause after the engine warms up will cause the engine to quit running. If it looks like fuel has been running down the side of the carb below the throttle shaft, replace or rebush. Just my .02.

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