How to cut double lead threads on an engine lathe?

To cut double lead threads on an engine lathe, first ensure your lathe is equipped with a suitable threading tool and that the lathe's gearing allows for double lead threading. Set the compound rest at a 29-degree angle for a 2-start thread. Use the threading dial to engage the feed at the appropriate point, making sure to adjust the spindle speed and feed rate for the desired thread pitch. As you cut, maintain consistent pressure and depth to achieve a clean thread finish.