GF30 Precision Rocker Cover by O.S. Engine OS4A004200  [OS4A004200]

Precision top cover for GF30 heads

This O.S. Engine OS4A004200 rocker cover serves as a precision top cap for GF30 nitro RC engines. It protects the rocker assembly from debris and contributes to more predictable head temperature during tuning and running.

Fitting is straightforward for those accustomed to nitro engine service: remove the previous cover, clean and check the sealing surface or gasket, place the replacement cover, and fasten using the original screws with cross-pattern tightening to ensure even seating. Refer to the engine's service instructions for any torque recommendations.

When tuning, a stable and rigid cover helps the head hold temperature more consistently. The machined alloy construction improves heat dispersal relative to thin stamped parts, and swapping a worn cover can restore correct sealing and component alignment in older GF30 engines.