Flooding is when gas is coming out of the top of the carburetor. Too much fuel is getting into the carburetor.
Another possible indication is when gas comes out of the throttle shaft.
Rochester 4 Jet flooding can be caused by a list of things:
Bad float - getting fuel inside the float which makes it too heavy.
Fuel pump pressure too high. Check your motors manual for correct pressure, probably around 4.5 lbs
Needle & seat leaking - the viton tip on the needle may have gotten damaged when installing. They are easily damaged. Look for any lines, or other abnormality's on the viton tip.
Is the gasket on the seat.
Was all the old gasket removed from the needle & seat?
Look for any cracks around the seat. Look for any chance of the gas going around the seat.
Check the float for any rubbing. The pontoons should be centered in the float bowl.
Make sure the needle is being pulled straight up by the float. It's possible the needle is getting stuck at an angle. This could be caused by the needle to float clip being installed incorrectly. It need to pull straight up.
You may be percolating. Engine gets hot, turn off key and the gas boils over. This is due to the low boiling point of the gas these days. Try different brands and grades. Make sure the fuel lines are away from the exhaust.
Fuel could be leaking around the power valve. Make sure the power piston moves up and down freely. Any sticking will leave the power valve open. The power valve stem should be straight. Make sure there is a gasket on the power valve and that there isn't any old gasket left behind.