Like crankshafts, rods have a finite fatigue life, depending upon the level of loading they have seen in the past. Various modifications have been routinely performed on factory rods to increase their durability. Shot-peening is a controlled process in which the rods are blasted with steel shot to add a compressive layer to the outside of the rod, increasing fatigue life. Racers would also polish a rod's beams in an effort to eliminate stress risers that can initiate a fatigue failure.
Aftermarket rods used to be outside the realm of a basic rebuild but are now affordable enough to consider in any engine build. Between the cost of resizing, new bolts, bushings, and any additional strengthening mods, the money invested in reconditioning a set of stock rods closes in on the price of aftermarket pieces. Aftermarket rods come in grades of forged steel from cheap to downright costly, and for the most part, quality goes up in scale with price. Consider the application and power level targeted; opt for enough rod to do the job, as a compromise here can cost the engine.
A successful engine rebuild begins with the fundamentals, which is what we have presented here. Be sure to tune in for Part Two, where the topics will be rings, quench, and balancing. Armed with this info, you'll have all the basic knowledge you need to start your own engine rebuild.
Rod reconditioning begins...
Rod reconditioning begins with a crack-inspection process and typically includes resizing the big end to factory specs on a rod machine. New bolts usually go in at the same time.
Fully prepping stock rods...
Fully prepping stock rods can involve magnaflux crack testing, straightness checking, resizing, adding new bolts, polishing the beam, indexing and correcting the center-to-center length, bushing the pin end, lightening, balancing, and shot-peening. In the old days, when aftermarket rod choices were limited, it wasn't uncommon to do all these things to a set of factory rods. That's too much to invest in a set of 30-year-old stock rods today.
Affordable aftermarket rods...
Affordable aftermarket rods are designed from the start with heavy-duty performance in mind. Rods such as the Scat H-beams shown here are surprisingly cost effective and come ready to run in a high-performance or race application.