Special Application (SA) crankcases can be ordered with spigot bore diameters from stock 3.680" to 4.630", and with crankcase deck heights up to 1.000" taller than stock. This is adequate for cylinder bore size up to 4 3?8". Cam chest is offset .250" to allow for these larger bore sizes. This offset requires the use of S&S Special Application tappet guides with corrected pushrod angles. Tappet guides are not included with crankcases, but can be purchased as an extra cost option. S&S SA big twin crankcases can be ordered machined for 1.500" diameter sprocket shaft for extreme racing applications. Crankcases can also be ordered without alternator machining for maximum strength in the left case.