1. Cylinder Head: Springs, Valves, and Valve Seats
Chapter 8
Cylinder Head: Springs, Valves, and Valve Seats

2. Objectives Analyze wear and damage to valves, springs, and seats
Understand theory related to valves, seats, springs, and other related parts
Select and perform correct repair
Reassemble cylinder head

3. Valve Springs Pressure on valve spring comes from three sources Spring
Pressure of combustion
Seat angle

4. Valve Spring Inspection
Visual inspection
Spring squareness
Free length
Spring tension

5. Pushrods Transmit motion from lifters to rocker arms
Hollow to allow oil to be transferred to rocker arms
Holes in cylinder head act as guide for push rod

6. Pushrods

7. Rocker Arms Shaft mounted or stud mounted
Iron, cast iron, or stamped steel
Different ratios (longer length)
Increasing ratio causes more movement of valves
Makes it possible to have smaller cam lobes

8. Rocker Arms

9. Valve Damage Wear on valve stem Valve burning Hoop stretching
Valve oxidation
Incorrect seating due to incorrect valve lash

10. Exhaust and Intake Valves
Intake valves are generally larger than exhaust
High carbon steel and tempered to resist corrosion
Valve stems are typically chrome plated
Some are sodium filled

11. Grinding Valves Chamfer valve tips Grinding stem tip
Should be done before grinding valve
Grinding stem tip
.010" to .015" should be removed from valves
Grinding valve face
1º interference angle

12. Grinding Valves

13. Grinding Valve Face First dress grinding stone
Adjust chuck to grab valve on unworn section of valve stem
Do not allow neck of valve to contact grinding stone

14. Grinding Valve Face Adjust grinder to proper valve angle
Grind only enough to remove any area of valve face that is worn

15. Valve Seats and Service
Most valve seats are integral and part of the cylinder head
Integral seats are induction hardened to reduce seat wear
Operate approximately 150º cooler than replaceable valve seats

16. Grinding or Cutting Seats
Most are finished to 45º or 30º
Seats are serviced with either grinding stones or carbide cutters
Pilot is installed into valve guide to center cutter

17. Grinding or Cutting Seats

18. Grinding Seats Advantages of grinding
Produces a smoother seat than cutting does
Can be used on extremely hard seats
Grinding stones must be dressed to true them to proper angle
Valve seat runout should be less than .002"

19. Grinding Seats

20. Carbide Cutters Advantages to carbide cutters Quiet Remain clean
Angles remain true
No grinding dust

21. Carbide Cutters

22. Seat Refinishing Angles
Sometimes all three angles are cut at once, which also cuts seats to correct height.
Typical three angle valve job
Face angle
Top angle
Throat angle

23. Seat Refinishing Angles

24. Reassembling Cylinder Head
Recheck installed height of valve spring
Grind tip or install new valves to achieve proper specification
Install valve shims under springs

25. Reassembling Cylinder Head
Thoroughly clean all guides
Lubricate valve stems
Install guide seals
Install valve, spring, retainer, and keepers