Assemble the dampener ends of springs (close wound coils marked with dye or lacquer) downward or next to lower spring seats.
5-77 Compress the valve springs with the valve spring compressor (ST-419) and assemble the valve retaining keys (27). If the valve is not seated properly the valve may be seated by using a wooden hammer handle against the tip of valve stem and hitting hammer with palm of hand. No other means should be used.
NOTE
Sodium-cooled exhaust valves are assembled with special keys and caps. Do not install caps until just before valve rockers are installed.
WARNING
5-81. Place a rubber cylinder base oil seal ring (figure 5-1) around the cylinder base assemble the application piston ring compressor over the top piston rings and install the cylinder over the piston, pushing the piston ring com-pressor ahead with the cylinder barrel. As the cylinder barrel approaches the crankcase, catch the piston ring compressor as it drops off the piston skirt. When the base of cylinder is seated on crankcase pad, secure the cylinder with 3/8 inch and 1/2 inch cylinder base nuts, tightening the nuts finger tight only.
5-82. To assure proper assembly of the crankcase halves and to eliminate the possibility of subsequent loosening of cylinder base nuts, a definite and specific sequence of tightening all crankcase and cylinder base nuts must be followed. Be certain that crankcase halves have been brought together, and fastenings secured as directed in Section 7 before installing cylinders. The cylinder base hold-down nuts are installed as described in the following paragraphs.
5-83. When all cylinders have been initially installed on the crankcase as described in paragraph 5-81, begin tightening all cylinder base nuts as described below, using the proper cylinder base nut wrenches and handle in con-junction with a suitable torque indicator. Torque wren-ches should employ the flexible beam design hydraulic principle or a dial indicator with rack and pinion.
NOTE
Do not under any circumstances assemble chrome plated piston rings in a chrome plated cylinder barrel. If in doubt as to the proper combination of rings to be used, refer to
the latest edition of Service Instruction No. 1037 or con-tact the Service Department, Lycoming Division.
5-78. Installation of Pistons and Cylinders. See that all preservative oil accumulation on cylinders and piston assemblies is washed off with solvent and thoroughly dried with compressed air. Immediately prior to assembly of piston and cylinder to the engine, space the ring gap and apply a generous coating of oil mixture as described
Before installing cylinder hold-down nuts, lubricate crankcase through stud threads with any one of the following lubricants, or combination of lubricants.
1.
90% SAE 50W engine oil and 10% STP.
2.
SAE 30 oil.
3.
Fel-Pro Food Grade AA Anti-Seize Lube.
a.
Tighten 1/2 inch hold down nuts to 300 inch pounds (25 foot pounds) torque.
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：莱康明发动机大修手册 OVERHAUL MANUAL LYCOMING 76 SERIES AIRCRAFT ENGINES(27)
