Cylinder Head Assembly: Service and Repair

Some engines may have an oversize camshaft. Engines having an oversize camshaft will be identified by a stamping marked ``.38/OC'' on the outside of the cylinder head above the No. 4 exhaust port. The camshaft will also be stamped ``.38/OC'' at the distributor drive end. If a cylinder head necessitating replacement incorporates an oversize camshaft, a standard size camshaft must be used with the replacement cylinder head. 1983---85 models incorporate three internal vent tubes located at the oil drain holes on the cylinder head assembly which replace an external hose vent system. The external vent system had a hose routed from the rear of the rocker cover to the lower area of the engine block. The function of the internal tube is to permit venting from the oil pan while simultaneously permitting engine oil to drain from the top of the cylinder head. Removing these tubes will restrict return oil flow to the oil pan. These tubes must be in place whenever removing or installing cylinder head assembly.
1. Disconnect battery ground cable.
2. On non-turbocharged engine models, disconnect heater hose from intake manifold. Remove air cleaner.
3. On turbocharged engine models, disconnect radiator upper hose from cylinder head, then remove air supply hose from air throttle body assembly.
4. On all models, disconnect electrical connector from cooling fan switch.
5. Remove PCV oil separator, if equipped.
6. Disconnect PCV hose from air cleaner assembly.
7. Remove rocker arm cover, drive belts, crankshaft pulley and timing belt cover.
8. Set No. 1 cylinder to TDC of compression stroke by turning crankshaft until pulley keyway is at 12 o'clock and camshaft sprocket keyway is at 6 o'clock. Then, remove distributor cap and spark plug wires as an assembly.
9. Using a suitable tool, loosen both timing belt tensioner attaching bolts.
10. Position timing belt tensioner as far left as possible and remove timing belt.
11. Disconnect EGR tube from EGR valve.
12. Disconnect choke cap electrical connector, if equipped.
13. Disconnect and cap fuel supply and return lines from engine.
14. Disconnect accelerator cable and speed control cable, if equipped.
15. On turbocharged engine models, disconnect EGO electrical connector and EGR valve vacuum hose.
16. On power steering models, remove thermactor pump, drive belt and bracket.
17. Disconnect altitude compensator from dash panel, if equipped.
18. Disconnect alternator air intake tube, if equipped and electrical connector.
19. Remove alternator and bracket.
20. On turbocharged models, disconnect air intake tube. Disconnect turbocharger oil supply tube from coolant outlet.
21. Disconnect exhaust pipe from exhaust manifold or turbocharger assembly.
22. On turbocharged engine models, disconnect oil drain from turbocharger.
23. Remove cylinder head bolts and washers. Discard bolts and washers.
24. Remove cylinder head, exhaust manifold, intake manifold and turbocharger, if equipped as an assembly. Before installing cylinder head, rotate crankshaft so pulley keyway is positioned at 9 o'clock (viewed from the front of the engine). Turn camshaft to position its keyway at 6 o'clock and install cylinder head. Then, turn crankshaft so pulley keyway is positioned at 12 o'clock. The camshaft and crankshaft are now properly timed and should not be rotated from this position until after the timing belt and sprockets have been installed.
25. Reverse procedure to install. Before FINAL installation of the cylinder head to the engine block, piston "squish height" must be checked. Squish height is the clearance of the piston dome to the cylinder head dome at piston TDC. No rework of the head gasket surfaces (slabbing), or use of replacement components (crankshaft, piston and connecting rod) causing the assembled "squish height" to over or under the tolerance specification is permitted. If no parts other than the cylinder head gasket are replaced, the piston squish height should be within specification. If parts other than the cylinder head gasket are replaced, check the squish height. If the squish height is not within specification, replace the parts again, and check piston squish height as follows:
a. Clean all gasket material from the mating surfaces on the cylinder head and engine block.
b. Place a small amount of soft lead solder on the piston spherical areas.
c. Rotate the crankshaft to lower the piston in the bore and install the head gasket and cylinder head. A compressed (used) head gasket is preferred.
d. Install used head bolts and tighten the cylinder head bolts to 30---44 ft. lbs. in sequence.
e. Rotate crankshaft to move the piston through its TDC position.
f. Remove the cylinder head and measure the thickness of the compressed solder to determine squish height at TDC. The solder should be .039---.070 inch.

Fig. 7 Cylinder head bolt tightening sequence:

26. Torque cylinder head bolts in sequence shown in Fig. 7, to 44 ft. lbs. Loosen all attaching bolts approximately 2 turns, and torque bolts again to 44 ft. lbs. After tightening all bolts, turn bolts an additional 90 degrees again in the same sequence. Complete bolt tightening sequence by turning cylinder head bolts an additional 90 degrees again in the same sequence. Refer to "Timing Belt, Replace" for belt tension data.