What was found
CREW REPORTS STRONG ODOR AFTER TURNING ON PACKS POST TAKE OFF. CREW DECLARED EMERGENCY, DAWNED O2 MASK, FOLLOW QRH AND RETURNED TO THE FIELD AND COMPLETED AN OVERWEIGHT LANDING WITH NO OTHER ISSUES. MAINTENANCE PERFORMED TROUBLESHOOTING ON ENG 1 AND ENG 2. COMPLETED MIN IDLE CHECKS FOR TYPE 2 CAUSE OF CABIN ODORS. BORESCOPE ON BOTH ENGINES NORMAL AND NO ABNORMAL ODORS NOTED REF TSM 05-50-00-810-831-A. AIRCRAFT WAS RETURNED TO SERVICE.