Good news for owners of TC 88 engines who need replacement crankcases for repair and high-performance applications 4-1/8" bore cases make really large displacement custom engines possible S&S cylinder stud pattern They feature a greater overall strength than stock cases, especially in the front motor mount area They use Timken style sprocket shaft bearings, and are clearanced for strokes up to and including 5" All passages between the crankcase cam support plate are O-ring sealed The cam chest has clearance for up to .675" lift cams Includes the S&S crankcase breather reed valve for Twin Cam 88 engines designed to eliminate oil carry-over and oil scavenging problems