Tightening method of high strength bolt

(1) Wet the bolt and joint surface with lubricating oil;

(2) Use pre-torque, the purpose is to have a common starting point for tightening

(3) Tighten the screws symmetrically in steps according to the specifications. If a bolt pin is slightly over-tightened, it must be fully loosened and then retightened.

(4) Notable matters

① Do not install spring washer and thrust washer when installing bolts

②It is possible to install hardened flat washers

③ During the overhaul period, the tensile deformation of the cylinder head bolts should be checked. The original length of the cylinder head bolts is 211 ± 0.5mm. After use, it becomes longer than 212.5mm and can no longer be used.

④ When tightening, use special tools, use six-sided socket wrench to tighten, do not use twelve-sided, because its strength is poor, easy to slip.

⑤ In principle, it is best to use the connecting rod bolt only once (referring to one overhaul period)