1 - angle of the working chamfer; 2 - outer angle of correction; 3 - internal angle of correction, 4 - circular diameter of the bearing surface of the valve seat; 5 - width of the working chamfer of the valve seat
The technology for lapping valve seats is identical for all engines. The valves should only be ground to the seat using a fine-grained grinding paste. Lapping of valve seats is carried out by rotational movement with frequent separation of the valve from the seat and its rotation. A tool is used to hold the valve «00.3.520» or «00.3.580» (pic. 3.6). Carefully remove traces of grinding paste after lapping.
Check the quality of grinding by the contact patch and filling the valve disc with kerosene. Fuel leakage through the valve guide is not permissible, re-lapping is required.