The Heart of a Record Breaker II: The Doctor is in



After Nick Hunter installed each set of rings on to their corresponding piston, he compressed them with a ring compressor and then installed each piston and rod combo into their respective bore.

A connecting rod experiences high loads, which distorts and ovalizes the connecting rod's big end bore.  This distortion causes the connecting rod bolt to undergo bending, tensile, and sheer stresses making the connecting rod bolt among the most highly stressed fasteners in an engine.  Due to the high levels of stress, K1 Technologies connecting rods are equipped with ARP 2000 connecting rod bolts for their high tensile strength and excellent notch toughness.

The correct way to measure a connecting rod bolt is by measuring  its length both before and after its installation.  This difference is called stretch.  Since the crank girdle kept us from being able to measure the stretch of the connecting rod bolt, we placed the connecting rod in a vice and used the “torque and angle” method to install the ARP connecting rod bolts.  

In this method, the connecting rod bolt is first cleaned and then lubricated with specific ARP bolt lubricant.  It's important to use the specific lubricant supplied with the bolts as different lubricants can reduce or increase friction and alter the amount of torque that the bolt requires to overcome that friction.  Once the bolt is lubed, it is torqued to the amount specified by ARP and afterwards, rotated a certain increment of degrees.  After installing the connecting rod bolt using the “torque and angle” method, we used a stretch gauge to ensure that the bolt was installed with the correct amount of preload.  Once we verified that a specific torque and angle yielded a specific amount of stretch, the K1 connecting rod was installed on the crankshaft and then fastened in place using the same torque and angle method.  

Once all four pistons and rods were attached to the crankshaft Nick Hunter turned his attention towards assembling the outer extremities of the engine block.

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