OS23818140 Thermo Insulator Compatible with O.S. 21B, 40E, 70C Engines by O.S. Engine  [OS23818140]

Thermal spacer for O.S. heads

This O.S. Engine OS23818140 thermo insulator is an RC-scale part made to sit with O.S. 21B, 40E and 70C engines and reduce heat transfer at the head area. It decreases direct conduction between mating surfaces to encourage more consistent head temperatures during operation and tuning sessions.

The insulator only supports the model codes shown in the product name, so check your engine stamping before purchasing. Most installations use the engine's original mounting hardware and are straightforward on standard glow head assemblies; ensure mating faces are clean and flat and confirm no interference with neighbouring components after refit.

As a tuning aid, it acts as a thermal buffer to limit temperature swings when trying needle or prop changes; monitor head temperature as part of regular setup and servicing. This product is intended for RC engines and must not be used on full-size engines.