THE ENGINE QUIT APPROXIMATELY FOUR MINUTES AFTER TAKEOFF, AND THE AIRPLANE HIT THE TOPS OF TREES THEN THE GROUND DURING THE FORCED LANDING. THE PILOT HAD STOPPED AT TWO AIRPORTS WHERE HE WAS UNABLE TO GET FUEL. HE SAID HE SAW ENOUGH FUEL IN THE TANK TO RUN THE ENGINE FOR FROM 45 MINUTES TO AN HOURS, AND THE GAUGE INDICATED 12 TO 13 GALLONS BEFORE TAKEOFF. THE ENGINE WAS INSTALLED IN ANOTHER AIRFRAME AFTER THE ACCIDENT AND IT STARTED AND RAN NORMALLY.