My 318 burns very rich, need your advice.

An Edelbrock 1406 is a great choice for a 318.

First, check the float level. They sometimes aren't quite right out of the box for whatever reason.

Next, with the engine at idle, pull one of the metering rod covers off and make sure the rods are all the way down at idle.

If they are all the way down, turn the mixture screws in until the engine dies. If you can kill the engine, it's not too rich. If you get the screws in all the way without killing it, go down a couple sizes on the main jets (switch front to rear).

Reading plugs can help you fine tune it. Bear in mind that the factory plugs are a couple heat ranges hotter than you want for todays gas. They will be white unless you are crazy rich and then they will just be black.