Torquing the Humble Rod Bolt

The humble rod bolt is one of the most stressed components in a piston engine.

Needless to say, if a rod bolt fails, there usually isn't much left of your engine. If you are aiming for big numbers, it pays to use the best, and they don't come much better than these #carrillo SPS CARR fasteners (well at least outside if F1 anyway!). While most people use a torque wrench to tighten rod bolts, the bolts actually act a little like a spring and to get the ultimate clamping force they need to be stretched a specific amount. In this case we are using a stretch gauge to measure the required 0.005-0.007" of stretch.