61RX-H and HGL Crankcase Replacement - O.S. Engine OS27921000  [OS27921000]

Technical overview and compatible engines

This crankcase is an RC-scale replacement part listed as O.S. Engine OS27921000 and specified for use with the 61RX-H and HGL engine designations referenced in the product name. It functions as the outer housing that locates the crankshaft and bearings, maintaining internal alignment during rebuilds and routine maintenance.

Compatibility is limited to the model codes shown in the product name, and the part is intended for hobby-grade RC nitro engine applications only. When preparing an engine for crankcase replacement, clean the mating surfaces, inspect the bearing seats, and verify internal gaskets and seals before final assembly to preserve reliable crankshaft alignment.

For tuning and setup, a correctly seated crankcase helps ensure consistent crankshaft runout and proper bearing preload, both of which can influence idle stability and overall power delivery in nitro RC engines. Replace the crankcase housing as needed and confirm fit with the engine’s crankpin and bearing sizes during trial assembly.

Supplied as a direct replacement housing for the 61RX-H and HGL engine references, this crankcase restores crankshaft alignment and internal geometry during engine rebuilds and maintenance procedures.