What was found
PILOT STATED THE ENGINE BECAME ROUGH AFTER TAKEOFF. RETURNED TO AIRPORT & LANDED. FOUND NR 1 CYLINDER TO BE COLDER THAN REST. PULLED ROCKER COVER & NOTED THE VALVES WERE NOT MOVING WHEN ROTATING ENGINE. PULLED ROCKER ARMS & PUSHRODS BUT FOUND NO PROBLEMS. REMOVED ENGINE FROM ACFT & BROUGHT TO REPAIR STATION. REMOVED A CYLINDER & FOUND CAMSHAFT BROKEN. DISASSEMBLED REMAINDER OF ENGINE. VALVES MOVED FREELY IN GUIDES & NO OTHER UNUSUAL PROBLEMS NOTED WITH ENGINE. CAMSHAFT INSTALLED NEW 236.48 HOURS PREVIOUSLY WITH NEW 72877 LIFTERS. CAMSHAFT IS BROKEN ABOUT 3 3/4" FROM FORWARD END. THE FRACTURE APPEARS TO ORIGINATE AT THE BASE OF LETTERS E AND L OF THE METAL STAMPED PART NUMBER, FORWARD OF THE NR 1 & 2 INTAKE LOBE. RECOMMEND THAT THE PART NUMBER BE APPLIED TO THE PART BY A METHOD OTHER THAN METAL STAMPING.