New stretch bolts should be used to prevent both torque loss and possible engine failure when rebuilding an engine. Measuring the old bolts will not indicate how much strength has been lost during the engines heat cycle.Kit Contains:8 Case Stretch Bolts (M10X82)8 Head Stretch Bolts (M11X147)6 Rocker Arm Stretch Bolts (M8X72) Will not work with the 300HP or 1603 Ace motors.