The crankshafts used in Hesco's engines are hand-selected, inspected, and magnafluxed. They are checked for straightness and any visible flaws. If necessary, they will be turned. They are turned to very precise tolerances, as dictated by the machine shop manager. The crankshafts are then deburred, balanced, and shot-peened. Once these steps are complete, they are cleaned and blown-dry, and inspected by a machinist.
The connecting rods used in Hesco's engines are one of the most scrutinized pieces in the engine. They are hand-picked for weight, length, and straightness. They are then placed into matched sets. Each connecting rod is deburred, the beams polished and shot-peened. If the rod is destined for a stroked engine, it will go to the CNC machine, where the pin end counter weight is precisely machined off for clearance to fit the forged stroker pistons. Once these steps are complete, the connecting rods are fitted with ARP rod bolts and each end machined to strict tolerances for the particular engine they are to be used in. The rods are then balanced and washed before final inspection and assembly onto the pistons.
All pistons go through the same routine, whether they're forged pistons destined for a race engine or a stock cast piston used as an everyday driver. They are checked for uniformity in weight and size. The quality of the casting or forging is checked and the pistons deburred. All forged pistons and any cast pistons a customer requests are sent to a ceramic coating room.
Once there, the piston rings' lands are taped, and the piston domes and skirts are media-blasted in preparation for coating. The pistons are washed in a solution and dried. They are preheated to a minimum of 90 degrees F before any coatings are applied. Once they are at the appropriate temperature, a ceramic coating is sprayed on the domes. A DFL moly coating is sprayed on the piston skirts. The tape is removed from the ring lands and the pistons baked at a minimum temperature of 300 degrees F for one hour.
Back in the machine shop, the piston pins are fitted to their respective tolerances using a Sunnen connecting rod machine. Then the pistons are balanced, cleaned, and given a final inspection. The pistons are then pressed on their respective connecting rods using Sunnen piston pin lubricant. The piston rings are removed from their packaging and each fitted to their cylinder. Piston rings are placed in the cylinder they best fit. The end gap is precisely measured on each ring to insure a perfect fit. The results are recorded on the build sheet. The rings are then installed on the pistons.
The main bearings are now installed in the block and main caps. The caps are placed in their respective location and torqued to spec. The counter bores are each measured and the numbers recorded on a build sheet. The crankshaft main and rod bearing journals are measured and these numbers are also recorded on the build sheet. Each connecting rod with its two bearing halves are assembled, the rod nuts are torqued, and these numbers are also recorded. With these figures, the engine builder is able to measure the oil clearance of each main and rod journal. If the clearance is to spec, he will prepare for final assembly of the short-block. The main bearings will get a generous amount of Redline Assembly Lube before the crankshaft is installed in the block. Before the crankshaft is installed, the upper half of the rear main seal will be installed. The lip of the seal will have a slight film of engine oil applied where it contacts the crankshaft to prevent tearing the seal when turning the crankshaft during assembly.