40100-ZVA-000 Engine (Lower) Case - Overview. The 40100-ZVA-000 Engine (Lower) Case is a vital component within Honda marine engine systems. It acts as the main housing and structural foundation for essential internal parts such as the crankshaft and gears. Engineered to ensure load-bearing integrity and protection of critical engine elements, this lower case plays a key role in supporting the overall mechanical system and maintaining seamless engine operation. Built to fit precisely with other