Figure 4-3. Ignition Wiring Diagram (Four Cylinder Engine)
OVERHAUL MANUAL LYCOMING 76 SERIES AIRCRAFT ENGINES Section5
ylinder,Piston
SECTION 5 andValveTrain
CYLINDERS, PISTONS AND VALVE TRAIN
5-1. The piston, being a reciprocating part, is normally grouped with the crankshaft in a theoretical breakdown of the engine into basic components. However, from a prac-tical standpoint, it is felt that the piston should be con-sidered with the cylinder insofar as overhaul procedures are concerned. For example, the basic configuration of the engine requires the removal and reassembly of the pistons at the same time the cylinders are removed or replaced.
5-2. For the purposes of the manual, the valve train will be considered as all parts of the valve operating mechanism beyond the camshaft, beginning with the hydraulic lifter assembly.
5-3. Although subject engines employ parallel valve cylinders with down exhaust, basic overhaul procedures are the same for all cylinders. The overhaul procedures described in this section will be applicable to all cylinder assemblies except as noted.
5-4. Either plain steel, chrome plated, or nitride hardened steel cylinders may be employed on the engines discussed in this overhaul manual. The color code for these cylinders is as follows:
a.
Plain steel All grey
b.
Chrome plated Orange paint on cylinder fins below spark plug hole.
c.
Nitride hardened Blue paint on cylinder fins steel below spark plug hole.
d.
.010 inch oversize Green when applied to
plain cylinders customer overhaul en-gines.
e. .020 inch oversize Yellow when applied to
plain cylinders customer overhaul en-gines.
NOTE
A yellow color, on fins ABOVE spark plug hole. indicates that long reach spark plugs are used.
REMOVAL FROM ENGINE
5-5. It is assumed that the ignition harness, intake pipes and primer lines have been previously removed.
5-6. Intercylinder Baffles. (where applicable) Using the in-tercylinder baffle tool (64885), release the baffle retaining hook so that it disengages the retainer. Remove the inter-cylinder baffle and hook from between the cylinders.
5-7. Oil Drain Tubes. Loosen hose clamps at lower end of tube and slide tube out of hose. Loosen gland nut at cylinder head fitting and remove drain tube.
5-8. Cylinder. See figure 5-1. Remove the rocker box cover
(13) and gaskets (12). Rotate the crankshaft to place the piston of no. 1 cylinder at top center of the compression stroke. This will place the valves in closed position and the piston extended away from the crankcase to avoid damage when cylinder is removed.
5-9. Remove the 5/16-24 self-locking nut (11) from the valve rocker fulcrum (10). Remove the valve rocker arms and fulcrum from cylinder. Remove the square washers (9) from the stud. Remove the push rods (2) by grasping the end and pulling through the shroud tube. Remove the 1/4-20 plain nut (7), lockplate (6) and spring (5). Pull shroud tubes out through the cylinder head and discard the shroud tube seals (3).
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