A crop harvesting machine with a cutter bar on a header frame has a height control system which uses depending sensor fingers arranged in contact with the ground so as to measure a height of the cutter bar above the ground. The sensor fingers are controllably retractable under actuation from an operator in the cab or automatically in response to prescribed conditions being met. The actuator used in retracting the sensor fingers can also be used to adjustably control ground pressure of the sensor fingers in the deployed position of the sensor fingers engaging the ground. The header height is adjusted using laterally spaced apart hydraulic linkages which can be operated at different elevations relative to one another responsive to different height signals relating height of opposing ends of the header frame relative to the ground to also control tilt of the header relative to the harvester frame.