Where the fuel screw is on theses engines, and how it works. Also here is a brief description in text.
When the engine is not under load, the governor (or throttle when under 3600rpm) keeps engine speed constant. When the engine is put under load, the governor compensates to get RPM back up by increasing the throttle. It usually, when under load, will immediately put the throttle to max fueling setting (where the fuel screw is set) until engine speed gets gets back to normal. Screwing out the fuel screw will allow the injection pump to pump out more fuel when under load. Screwing it in will do the exact opposite.
