The 6.2L crankshaft (Figure 2-20) is made of nodular iron with deep rolled fillets. Nodular iron, also called ductile iron, is one of three common types of cast iron. The others are grey iron and malleable iron.
Nodular iron is made by treating a low-sulfur, grey-ironlike alloy with magnesium. Addition of the magnesium forms the free carbon into the spheroids — or nodules — which give nodular iron the best combination of ductility and strength of the three common cast irons. Depending on the application, nodular iron castings can be used as cast (without heat treatment), annealed for greater ductility as required or heat-treated to higher hardness for greater strength and wear resistance.
It has 5 main bearing journals. These main bearing journals are classed by O.D. into 3 classes so that the main bearing can be matched to the proper size bearing insert in the main bearing cap. The diameter of the main journals is controlled to the following total range #1 through 4 — 74.917/74.941 mm and #5 — 74.912/74.936 mm. Each of these ranges is divided into 3 sizes. The pin journal diameter range is 60.913/60.939 mm. This range is divided into 2 sizes.