Universal Overhead Valve Spring Compressor Keep Hands Clear of Fan, Belts and Pulleys Since Slight Crankshaft Rotation Will Occur Tool Maintains Constant Length As Spring is Compressed Use With 901DD or 2992D Air Hold Fittings to Keep Valve in Place Caution: Vehicle Must Be Placed in Park/Neutral Before Applying Air Pressure, Otherwise Vehicle May Move Remove Valve Springs on Most Cars With Overhead Valves Without Removing the Cylinder Head Offset Jaws Grip the Valve Spring in Parallel Compression