What is the correct float setting for this carburetor and where do you measure from?
When I don't have a spec for the float setting, I set it parallel w/the body when it's upside down, (valve closed) and go from there. Doesn't take long to find out ifn you have to raise or lower the float. Usually, if anything, it has to be lowered. Go in 1/16" increments.
Make sure the hole in the bottom of that carb is open all the way through and not rusted shut. Run a piece of wire through to make sure. The L4 needs that air hole to work properly.
Also, Peter, if that is going on a car with a cowl tank,you may have to do a little extra tinkering. With a full tank of gas, you may find it likes to leak. This is due to the cowl tank having more head pressure.The factory offered a fix for this in the form of a more buoyant float. L-4's seem to do this more than NH's for some reason. L-4 is good carburetor.
You may also find you must run a hot air pipe. L-4's like to frost up intakes. They have a little flapper that increases mixture velocity.