The experience of checking the length of the bearing bush is as follows: install the bearing bush, install the bearing bush cover, tighten the bolt at one end according to the specified torque value, insert a 0.05mm thick gasket between the cover at the other end and the plane of the bearing bush seat, when the torque of tightening the bolt at the end reaches 10-20n · m, if the gasket can not be pulled out, it means that the bearing length is too long, and the end without locating tenon should be filed down; If the gasket can be pulled out, it means that the length of bearing bush is suitable; If the gasket cannot be pulled out without tightening to the specified torque value, it indicates that the bearing bush is too short and should be re matched. After the new bearing bush is put into the bearing bush seat, the curvature radius of the bearing bush is required to be greater than that of the seat hole. When the bearing bush is installed into the seat hole, it can closely fit with the bearing seat hole by the elastic force of the bearing bush itself to facilitate heat dissipation. Check whether the bearing bush has a mute sound. Tap the back of the bearing bush to listen. If there is a mute sound, it indicates that the alloy is not firmly combined with the base plate, so it should be re matched. When selecting bearing bush, the fit clearance must be checked. During inspection, measure the bearing bush and journal with cylinder gauge and micrometer, and the difference is the fit clearance. The inspection method for the fit clearance of bearing bush is as follows: for the connecting rod bush, apply a thin layer of oil on the bearing bush, put the connecting rod on the corresponding journal, tighten the bolts according to the specified torque value, and then swing the connecting rod by hand, which can rotate 1 ~ 1 / 2 circle, pull the connecting rod along the axis direction, and it meets the requirements if there is no clearance feeling; For the curved bearing bush, apply oil on the surface of each journal and bearing bush, install the crankshaft, tighten the bolts according to the specified torque value, and pull the crankshaft with both hands. It is appropriate that the crankshaft can rotate 1 / 2 turn, and the rotation is light, uniform and without blocking.