O.S. Engine OS45060309 Replacement Valve Spring Seat for FS-26S, FS-40S and FS-48S  [OS45060309]

Precision seat to stabilise valve timing

This valve spring seat is an RC-scale replacement part intended for the O.S. Engine FS-26S, FS-40S and FS-48S engine family named in the model title. It creates a precise seating area so valve springs operate on a consistent plane, which helps when fine-tuning valve timing and performance on nitro model engines.

For tuning work, install the seat with care: remove the head, verify spring and retainer alignment, and press the seat squarely to the guide. After seating, run a verification check of valve movement to ensure timing remains repeatable across runs.

Avoid heavy-handed workshop techniques; this part is engineered for model use and should be manipulated with hobby-appropriate tools to maintain the intended fit and function.