>Technical Advice

Torque Procedures and Specifications

The method needed to achieve proper torque and fastener stretch will be identical for all connecting rods manufactured within our facility regardless of model or fastener type. The torque value will be determined by the size of the head of the fastener. Reference the list below for proper torque specifications.

Before assembly in the engine takes place , the connecting rods must be taken apart , cleansed and dried with compressed air. Take caution to put the fastener back in the same thread from which it was removed. It is imperative that the serrations on the rod cap and rod body be free of oil, dirt and debris. Use extra caution when handling the rod cap and the rod body, as the serrations must remain undamaged for proper fitment and assembly. Once in the engine place the rod cap on the rod body. Lubricate the threads of the fastener with 40W motor oil for all HA Series connecting rods and 50W for all other series connecting rods. Thread the fastener in to the rod body until the head of the fastener just contacts the hat washer in the cap. Slowly and steadily torque each fastener once to the specified torque value, and do not step torque the fasteners. The use of the step torque method and lubricants other than listed above could lead to improper stretch of the fasteners. The use of a stretch gauge can be used to verify proper stretch, however one is not required for proper installation.

3/8" head ARP Fastener: 65 ft/lbs torque, 0.0050"-0.0060" fastener stretch

7/16" head ARP Fastener: 90 ft/lbs torque, 0.0055"-0.0065" fastener stretch

1/2" head ARP Fastener: 105 ft/lbs torque, 0.0060"-0.0085" fastener stretch

Clearances

Per our recommendation the vertical bearing clearance for connecting rods for drag race use should be 0.0030" and 0.0035" and the side clearance between connecting rods on the same rod journal should be a minimum of 0.0150" and a maximum of 0.0200". Our recommendation for wrist pin oil clearance is 0.0012" for most applications.