How do you set a quadar jet carb on a Chevy?

To do it right you need an exhaust gas analyzer.

Install the carburetor and try to get it to a point that it functions somewhat normally. This is where experience comes in and you can figure out what is about right for the engine, carb and altitude.

Run the engine at operating temperature and either on a dyno or out on the road. Watch the exhaust gas analyzer, if the engine is running too rich you'll need to install smaller jets/metering rods. If it's running too lean, go larger.

Once the jets are set up properly then you can adjust the idle mixture. The carburetor instructions should tell you the basics but in effect, turn the idle mix IN until the engine idle starts to load up, then turn it out to the point that it clears up. The book will tell you how far BEYOND that point to turn the idle mix screw. I usually go 1 to 1-1/2 turns beyond if I don't have a book in front of me.