Pontiac Firebird SD-455 Engine - New-Age Super Duty
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Compare the boring procedure to a plowed field. The field will have fractures all around each furrow made by the plow. Likewise, the boring tool will fracture the metal on the sides as well as below the depth of the cut. Because of this, it is imperative to leave a minimum of 0.002-inch stock in the cylinder for finish honing to the final dimension (our block was 4.185 inches). The cylinder hone smoothes and provides a special finish to the cylinder wall called a crosshatch, which allows the rings to seal and minimizes the combustion and oil passing by them. A hone with a given grit size will produce a specified cylinder-surface finish but can be modified through cutting pressure, speed, and the number of strokes. RaceKrafters uses a brand new $60,000 Sunnen computerized automatic cylinder hone, the same type employed by NHRA and NASCAR teams. The key to this piece of equipment is the cylinder-wall finish it can provide, something that was not available in 1974 when Pontiac built this engine. RaceKrafters then confirms the crosshatch on the cylinder wall using a tool called a profilometer. A deck plate is used to simulate the twisting force of the cylinder-head bolts. View Related Article
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