Page 4 of Crankshafts and Crank Kits by NAPA

simply stated the index controls when the pistons will get to the top of the stroke this is the mechanical timing of the engine and is absolutely fixed when the rod journal is ground virtually all of the high volume crankshaft regrinders offset grind the rod journals and change the crankshaft s index or stroke the crankshaft now has its mechanical timing changed and the engine will not operate at optimum performance why do re-grinders change the journals offset quite simply it is the fastest cheapest and easiest way to return a worn journal to round if the wear area on the journal is 0.020 deep grinding the diameter down 0.020 in size could restore the entire journal this requires a lot of time and grinding but it would again be back to round the commonly selected alternative is to center between the worn area and the opposite side of the journal now only 0.010 needs to be ground from the outside dimension and the crank is once again round by doing this we have changed the physical center of the journal by 0.010 depending on which direction the center moved we have changed the index of the crankshaft or have increased or decreased the stroke the motor will never run the same this one cylinder will be mechanically out of time or will have too much or too little compression can the index be returned to the original factory blueprint spec the answer is yes by adding metal to the worn area the original centerline can be maintained in the past this was done by welding the journal and grinding the result was unsatisfactory high voltage and amperage welders heated the surface unevenly and cracks developed as the area cooled stress cracks from journal overheating developed in the radius these cranks were susceptible to breakage under high load conditions in an engine even worse during the weld process moisture and oxygen created voids and pitting of the surface the next generation process offered improvement a black flux material is poured onto the weld area to slow cooling and reduce checkering or cracking the high voltage and amperage still resulted in radius cracking and the failure rate was abnormally high finally a process now used to harden camshaft lobes for race engine such as nascar nextel cup cars was perfected for crankshafts a blend of three inert gasses forms a cloud around the weld area all moisture and oxygen are displaced then a weld material designed for low voltage/amperage use is applied to the shaft there is no cracking checkering pitting or stress cracking due to overheating the journal plus the crank can maintain an original index and stroke any journal repair performed on hi-tech blueprint series crankshafts is done using this method stress relieving as metal flexes stress risers can form in the grain structure the metal fatigues and breaks flex a paper clip back and forth and it soon looses its stiffness and breaks into two pieces these stresses can be relieved from metals by annealing using heat or shot peening or both hi-tech s blueprint series cranks are first heated until stress risers are reduced and then shot peened in 4-minute cycles the result is a stronger shaft that also retains straightness bushings many crank grinders leave the bushings that are required for transmission installation out of the back of each crank this allows them to use one part number to cover several applications the problem created for the installer is that the crank cannot be installed without these bushings imagine being almost done with the job and realizing that you have to order bushings before you can finish hi-tech prevents this problem by including and installing the required bushings in each crank the crankshaft on the right shows the bushing that hi-tech includes protection after paying attention to all the other details the crank deserves protection blueprint series cranks receive a rust inhibitor spray coating then each is carefully placed in a heavy reinforced corrugated carton and encapsulated with expanding foam for protection dimensions each crank is foamed-in-place inside a heavy duty corrugated box this protects the precision machined surfaces during transit the factory print contains many other critical dimensions blueprint series cranks follow these with closer tolerances than observed by re-grinders the following tolerances are just a few of the critical dimensions that are maintained:

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