Volvo L90 and L120 valve guide
The valve guide in Volvo L90 and L120 loader engines ensures precise valve stem alignment and maintains concentricity with the valve seat. It is typically manufactured from alloyed cast iron, phosphor bronze, or aluminum bronze with a hardness range of 180 to 220 HB. The internal diameter for intake valves is approximately 8.00 mm with a tolerance of 0.02 mm, while exhaust guides are around 8.03 mm. The permissible clearance between the valve stem and guide is set between 0.03 and 0.06 mm to balance lubrication and sealing efficiency. Guide length generally ranges from 45 to 55 mm, and thermal resistance is maintained up to 400°C under continuous engine operation.
The valve guide design promotes efficient heat transfer from the valve stem to the cylinder head. The thermal conductivity of the bronze alloy used is approximately 50 to 60 W/m·K. The interference fit into the cylinder head is controlled between 0.04 and 0.07 mm to prevent rotation or loosening. Expected service life exceeds 8,000 operating hours under heavy-duty working conditions. Concentricity tolerance below 0.02 mm minimizes uneven wear and ensures stable combustion performance in high-load diesel engines.
