O.S. Engine OS29121400 120AX Gasket Set  [OS29121400]

Overview of the 120AX sealing kit

This gasket set is an OEM replacement pack for the 120AX engine family and is supplied under the O.S. Engine part number OS29121400. It is intended to be used when carrying out inspection, teardown, or rebuild procedures on matching 120AX engines.

Compatibility is confined to engines marked 120AX; always verify the exact model code to confirm fitment. The kit restores sealing between mating surfaces such as the crankcase, head and backplate after maintenance or component replacement.

Installation notes: make sure mating surfaces are clean and clear of all old gasket material, inspect components for distortion or damage before installing new gaskets, and adhere to O.S. Engine torque and assembly instructions for fasteners during reassembly. Proper sealing maintains compression and consistent engine behaviour across different settings.

Role in performance: while gaskets themselves do not adjust tuning parameters, correct sealing is vital for consistent compression and predictable needle-valve performance, so replacing degraded gaskets is part of standard engine care.