On a LA40 a 10x6 would be more appropriate IMO. In addition to da Rock said in post #5, you should be able to idle the engine for 30 seconds and then move it immediately to WOT and have it accelerate without stumbling or quitting.

As he said, if a new or newer engine, you can expect to need to retune it following complete break-in. After break-in the idle screw can be virtually forgotten unless you accidentally move it or experience MAJOR atmospheric changes like moving into the mountains.