QSB4.5 and QSB6.7 Engine Identification Section E - Engine and System Identification Page E-3 1 Engine serial number 2 Engine model information 3 Control parts list (CPL) 4 Valve lash (overhead) setting 5 Horsepower and rpm rating. 1 Engine serial number 2 Engine model information 3 Horsepower and rpm rating 4 Valve lash (overhead) setting.