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The engine valve has direct affect on the sealing and other performance of the engine. In poor working conditions, it repels strong mechanical load, high temperature and chemical corrosion. As the important part in the engine, the valve has to be installed and used in correct way. In the process of unpacking and transportation, the valve should not be knocked or crashed. It can not be used to bear overload and addictive stress, or the valve will deform and fail, leading to early damage.

When the valve is installed, the precautions below should be read carefully.
1. Different types of valves in the same series can not be mixed in one carton.
2. When replacing the valve, users should also replace the valve guide and spring of the valve. The old valve guide will increase the engine oil consumption and carbon deposition. Yet the carbon deposition will lead to the increasing of working temperature of the valve, whose service life will be shortened. As the old valve spring performs with declined elasticity, it has bad effect on the durability of the valve and the power of the engine.
3. After the new guide is connected to the cylinder head, users should regulate its circular degree and the inner diameter by reamer to make the space between the valve stem and the valve guide hole to conform to the regulations in the instructions. If the space is 0.13mm for the valve stem in less than 8mm diameter and it is 0.16mm for the valve stem in more than 8mm diameter, the valve or the guide should be changed. Otherwise, it will lead to the early damage of the valve. By the way, there is no need to process the machined valve stem.
4. If the valve seat is deformed or burned, it should be cut and grinded but not be mended only in the way of mutual lapping with the valve. The valve seat can not be mended should be replaced. The repaired or new valve seat mouth should be coaxial with the dust hole and the proper alignment deviation is 0.03mm. When the valve is installed in the valve seat, the subsidence of the valve and the cylinder head should conform to the engine instructions.
5. The mutual lapping of the valve and the valve seat should be done lightly to ensure the tightness of the valve. During the lapping, coarse abrasives are not available and the valve seat should contact with the lower part of the conical surface of the valve. In addition, the valve and the valve seat should be sealed tightly, or the engine power will decline and the valve will be damaged early.
6. After lapping, the abrasives should be cleaned with kerosene. The valve stem and the guide should be lubricated with clean engine oil.
7. New valve oil seal should be mounted.
8. Users should select the eligible valve collet, which has no flash burr. After lapping, the valve collet should match with the valve neck. The taper hole of the spring seat should be contacted well with the outer conical surface of the valve collet.
9. Without knocking the end of the valve stem, users should install the valve collet stably. Otherwise, it will cause the valve to shake and the valve collet will damage the valve neck by clamping, and then the valve collet will break at the valve neck part.
10. It is important to adjust the valve clearance according to the engine instructions. After 800 or 1000km running of the vehicle, it is better to correct the valve clearance again. If the valve clearance is too small, the working temperature of the valve will increase and the conical surface will be worn early. When the valve clearance is over large, the valve will impact the valve seat with big noise. In these two conditions, the valve neck will be broken.