PA12 ON FERRY FLT SUFFERED FUEL STARVATION. PLT AND PLANE UNHARMED AFTER LNDG ON DIRT ROAD.

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I WAS FERRYING THIS ACFT. I DID NOT HAVE VERY MANY HRS IN TYPE AND ZERO HRS ON THIS PARTICULAR ACFT. I PERFORMED A VERY DETAILED PREFLT BEFORE DEP. I FOUND BOTH FUEL TANKS TO BE FULL. I WAS TOLD THE FUEL BURN WOULD BE 7.5 TO 8.5 GPH. USING THOSE NUMBERS; I CALCULATED A 4 - 4.5 FUEL BURN; TO EMPTY. AT 3 HRS FLT TIME I HAD ENG FAILURE. I HAD BEEN USING MY WATCH AND AN ONBOARD TIMER TO KEEP TRACK OF MY TIME ENRTE AND TO PERIODICALLY SWITCH TANKS. I ALSO WAS WATCHING THE SIGHT GAUGES ON THE INSIDE OF THE CABIN. AT THE TIME OF THE OCCURRENCE MY L TANK (THE ONE I WAS FEEDING FROM) INDICATED 3/4 - 1/2. THE R TANK INDICATED 1/2 - 1/4. I ALSO FOUND THAT I HAD TO LEAN OUT THE MIXTURE ALMOST TO THE POINT OF CUTOFF FOR THE ENG TO PERFORM BEST. WHEN THE ENG QUIT; I IMMEDIATELY TURNED R; TOWARDS ZZZ ARPT; INFORMED ZZZ1 APCH THAT I NEEDED TO LAND ASAP. I SWITCHED TO THE R TANK AND THE MOTOR DID NOT RESTART. I TRIED THE MIXTURE. I PUMPED THE THROTTLE; EVEN TRIED TO PRIME -- NOTHING. I INFORMED ATC THAT I WAS NOT GOING TO MAKE THE ARPT AND I THEN PICKED OUT A SUITABLE DIRT ROAD TO LAND ON. MY LNDG WAS UNEVENTFUL; MEANING IT WENT SMOOTHLY. I WAS UNINJURED AND THE ACFT WAS NOT DAMAGED. UPON INSPECTION BY THE FAA AND A MECH; FUEL WAS NOT PRESENT IN THE L TANK AND POSSIBLY 1 OR 2 GALLONS IN THE R TANK. THE LOW SUMP AND CARB FUEL BOWL HAD FUEL; THE AIRPLANE STARTED AND RAN FINE PRIOR TO PUTTING ANY FUEL IN THE TANK. BOTH GLASS FUEL GAUGES SHOWED 'EMPTY.' THE MECH CLRED THE ACFT TO FLY. THE FAA INSPECTOR 'RELEASED' ME AND WE PLACED 5 GALLONS IN EACH TANK; I FLEW THE ACFT OFF OF THE DIRT ROAD TO ZZZ AND PARKED FOR THE NIGHT. THE NEXT DAY AFTER THE MECHS FINISHED ALL NECESSARY CHKS I CONTINUED ON THE JOURNEY. I FOUND THE FUEL BURN TO BE QUITE EXCESSIVE -- NOT 8.5 GPH BUT MORE CLOSE TO 13 GPH. I WAS TO FLY ONLY 45 MORE MINS ON THAT LEG BEFORE I HAD TO LAND. MY FOLLOWING LEGS WERE ALL LIMITED TO 2 HRS; SO I COULD MONITOR FUEL BURN. I USED 9.8 - 12.2 - 8.7 - 7.6 GPH ON THE FOLLOWING LEGS. I HAVE NOT YET FOUND THE GPH FOR MY FINAL LEG. THE ACFT PERFORMED WELL FOR THE WHOLE TRIP AFTER THE INCIDENT. UPON DOING SOME INVESTIGATIONS MYSELF; I BELIEVE THE AIRPLANE BURNED MORE FUEL THAN ADVERTISED DURING MY FIRST LEG. I THOUGHT I HAD 1 - 1 1/2 HRS FUEL LEFT ON BOARD. I HAVE BEEN TOLD THAT THE PA-12 MUST BE LEVEL INFLT WHEN LOW ON FUEL FOR THE FUEL TO BE PICKED UP WHEN SWITCHED FROM TANK-TO-TANK. I KNOW BOTH TANKS WERE FULL WHEN I LEFT AND I ALSO DO NOT BELIEVE ANY FUEL VENTED OR LEAKED OUT INFLT. IN THE FUTURE; I MUST MAKE SHORT FIRST LEG SECOND LEG IN ACFT WITH UNRELIABLE FUEL GAUGES. FIRST LEGS THAT ARE AS CLOSE TO 1 HR SO I CAN BETTER JUDGE ACTUAL FUEL BURN; NOT TO JUST TAKE OWNER'S WORDS FOR WHAT THE ENG BURNS. I HAVE ALWAYS FLOWN DAYTIME VFR WHEN FERRYING ANY ACFT DUE TO PROBS THAT CAN ARISE FROM ANY UNFAMILIARITIES OR MALFUNCTIONS AND I PLAN ON ADHERING TO THIS POLICY IN THE FUTURE. ALSO MAINTAINING STRICT FUEL MGMNT PROCS.