S&S Cycle 84-91 BT w/ 3-5/8in Bore Super Stock Alternator Style Crankcase - Natural

What you get with this S&S Cycle Super Stock Alternator Style Crankcase is a well-built foundation for your Big Twin engine, designed for both stock replacement and high-performance builds. This crankcase is specifically machined to accommodate a 3-5/8 inch bore and is clearanced for 38 amp alternator stators, making it a solid choice for your 1984-1991 Big Twin project. It's also compatible with stock flywheel assemblies, primary covers, and gearcovers, simplifying the integration into your existing setup.

Beyond just being a replacement part, this crankcase offers some notable features for improved performance and easier integration. It's machined to accept a crank position sensor, which is essential for stock EFI applications and makes installing S&S's own IST Ignition and VFI Fuel Injection systems straightforward. The design includes a ported breather passageway and a machined breather window to efficiently move air/oil mist from the flywheel cavity to the cam chest with minimal restriction. For engines larger than 95 cubic inches, S&S recommends using both crankcase breathers for optimal venting, though you can also vent through the cylinder heads or a combination of both. The cam chest oil pick-up has been relocated to enhance gear case scavenging and virtually eliminate oil carry-over during sustained high speeds. Plus, it's machined to accept the stock oil filter assembly found on 1984-1991 Big Twins and is clearanced for strokes as long as 5 inches.