Inspection and testing are...
Inspection and testing are part of the ongoing quality control at ARP. The instrument holding the stud measures diameter consistency on body and threads. In the other photo, a torque wrench is being used to properly preload (prestress) a stud, an essential part of bolt and stud installation.
Second, use a good quality lubricant. Many tension fasteners must be lubri-cated to achieve proper tension strength for the bolt. Motor oil is one good lubricant, but ARP makes a special moly lube for properly preloading bolts. Properly seeding and preloading bolts ensures that the backup torque value (that which is required to loosen the bolt) will be as close as possible to the bring-up (tightening) torque value. That will prevent any possibility of loosening problems due to vibrations and harmonics. Consult ARP or a qualified speed shop for more information on this.
Third, make sure bolts and nuts don't bind when handtightening. Any undue friction when tightening means there is an obstruction, causing a false preload condition. Clean parts and retap threads if necessary.
Fourth, for most tension-loading applications, don't use locking devices. They prevent proper preloading to take place. Due to heat and vibration, the locking mechanism is subject to change and could result in a loosening of the bolts. Properly torqued bolts will withstand all the changing dynamics of a bolt or stud application. Note: It is essential to have a thorough understanding of proper torque values for a given bolt in a given application. Obtain a torque table from ARP or other fastener manufacturer, and when in doubt, contact the company for expert advice.
Finally, do the research necessary for complete fastener information. That knowledge and its application might save you a race car or engine someday-not to mention a heap of money.