Disassembly
1. Place the cylinder head in the front and rear parts on two wooden blocks.
2. Remove the intake manifold together with the carburetor, as well as the exhaust manifold.
3. Remove the distributor and fuel pump.
4. Remove the camshaft bearing cap from the flywheel side.
5. Remove the camshaft drive pulley, holding it with a special rod used to install the valve timing.
6. Remove the plastic cover and oil line.
7. Remove the five camshaft bearing caps and then remove the camshaft itself.
8. Using a special suction cup, remove the tappets. Mark the tappets and adjusting plates.
9. Using a standard tool, compress the valve spring.
10. Remove the valve crackers.
11. Remove the spring compressor and remove the upper spring plate.
12. Remove the valve spring.
13. Remove the lower valve spring plate.
14. Remove the valve from the back of the head. The valves are removed in order, starting from the timing drive side. The valves must be marked with adhesive tape or laid out so that they fit into place during assembly.
15. Remove the oil seals.
16. Remove the additional oil filter from the oil channel.
17. Clean the cylinder head mating surfaces (magnus Magstrip or Framet Decaploc should be used).
18. Clean and thoroughly blow out all parts with compressed air.
Caution! Do not use tools that may scratch the parts being cleaned.
19. Using a ruler and feeler gauge, check the flatness of the lower surface of the cylinder head joint. The maximum flatness is 0.05 mm. The manufacturer does not allow grinding of the lower surface of the cylinder head joint during service repairs.
Replacing valve guides
If too much clearance is found in the valve guides, the guides should be replaced. This operation should be entrusted to a specialized service station.
Attention! When replacing a valve guide, it is necessary to regrind the corresponding valve seat.
Lapping valves
When grinding valves, use only fine-grained polishing paste.
1. Lubricate the surface of the valve seat with a small amount of paste and install the valve in the corresponding seat. Press the rubber suction cup tightly to the valve plate and rotate the valve in one direction or the other.
2. After finishing the grinding process, thoroughly clean all parts from dirt and paste and check the valve seat and plate. A solid matte ring should be visible on both parts, which indicates the width of the valve chamfer.
3. Apply pencil strokes on the valve plate ring at a distance of approximately 1 mm evenly around the circumference, then insert the valve into the guide sleeve and turn it 90°, while lightly pressing on the valve.
4. Remove the valve and check for any marks. If all marks are erased, the valve can be finally installed. Otherwise, the grinding operation must be repeated.
5. Check the valve plate seating width.
6. Check the tightness of the fit.
7. After grinding and lapping the valves, the cylinder head should be thoroughly cleaned.
Cylinder head assembly
Installing the oil seal on the valve stem
1. Perform the actions in reverse order to the disassembly process.
2. For each valve, perform the following steps in the following order:
- place the valve in the guide, observing the appropriate position;
- install a new valve stem seal on the valve stem;
- install the lower plate, spring and upper plate;
- use a special device to compress the valve spring and insert crackers.
3. Remove the spring compressor.
4. Install the pushers in their original places (as before disassembly) together with the corresponding adjustment plates.
5. Install the camshaft, secure the bearing caps and the camshaft side flange, tighten the bearing caps to 15 Nm.
6. Install the timing side bearing seal (device 7.0153 E).
7. Install the pulley.
8. Check and adjust the valve clearance. The final steps for assembling the cylinder head are performed in the reverse order of the disassembly process, i.e. install the oil line, the bearing cover on the flywheel side, the fuel pump, the distributor, the intake and exhaust manifolds (the gaskets should be replaced).
9. Install coolant temperature sensors (if they were removed).
10. Install an additional oil filter in the cylinder head oil line.
11. Use a special rod to fix the camshaft pulley in the valve timing installation position.