H4D: Cylinder head and top end

ID: 160208

Description: Much of the following information is taken from...

Steps:

1. Nominal cylinder head height: 125 mm.
2. Maximum cylinder head flatness defect: 0.3 mm. Resurfacing prohibited (RTA).
3. Cylinder head fastener screws: 1st pass to 25 N·m, 2nd pass to 270° ± 20°.
4. Camshaft bearing screws: 1st pass to 5 N·m, 2nd pass to 10 N·m.
5. Follow the tightening sequences for the cylinder head fastener screws and the camshaft bearing screws.
6. These screws are for single use.
7. Lubrication of cylinder head fastener screws: under heads and on threads.

8. Notches are visible, intended to allow passage for the dual-spray injector nozzles.
9. It would be necessary to mill new holes to switch to a single-spray dual-injector system. There does not seem to be much room, as shown by the gasket surface mark.
10. The intake manifold design would also need to be revised to allow for this modification.
11. The intake is likely at its optimal diameter for efficiency. Increasing it could eventually lead to detrimental effects.

12. You can see the presence of our 4 valves. The intake is at the bottom, while the exhaust is at the top in this image.

13. First photo: timing side without the pulleys.

14. Note that the exhaust ports are narrower than the intake ports.

15. This view allows us to see the hydraulic valve lifters with their black DLC (Diamond Like Carbon) coating.

16. It may be necessary to follow other instructions in addition to these.
17. Tightening sequences from the RTA.

18. 13 N.m
19. Timing cover screws: a tightening sequence must be followed.
20. These parts of the gasket are in the void and could be subject to breakage over time. Replace these gaskets without hesitation if the engine is removed.

21. The H4D engine uses hydraulic valve lifters with a DLC (Diamond Like Carbon) finish.

22. 70 N⋅m