feeder1h.cpp

#include <Servo.h>

Servo myservo;

const int servoPin = 9;
const int ledPin = 13;

void setup() {
  myservo.attach(servoPin);
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);
  myservo.write(180);
  delay(1000);
  myservo.detach();
}

void loop() {
  myservo.attach(servoPin);
  myservo.write(30);
  delay(575);
  myservo.write(180);
  delay(1500);
  myservo.detach();
  delay(3600000);
}

Where to change the code when the interval is 4 hours