201kb - Cylinder Head Service

Question 1

What are valve springs inspected for?

Answer 1

• Nicks, cracks, corrosion, wear
• Squareness (tilt/lean)
• Tension
• Length

201kb pg. 2

Question 2

What is spring free length?

Answer 2

Uncompressed spring length

201kb pg. 3

Question 3

What is spring squareness?

Answer 3

Measurement of the lean in a spring. Maximum allowed variation is generally 1/16”

201kb pg. 3

Question 4

What does low valve spring tension cause?

Answer 4

• Poor valve sealing
• Poor valve cooling
• Valve float at high engine speeds

201kb pg. 5

Question 5

What is valve spring installed height?

Answer 5

Measurement from spring seat on cylinder head to underside of spring retainer.

201kb pg. 14

Question 6

How can the valve spring installed height be modified?

Answer 6

Increased by adding shims under the spring. No more than 2 shims with maximum thickness of 0.060”

201kb pg. 14

Question 7

A vacuum gauge can be used to check valve sealing. What amount of vacuum is used for the test and what constitutes excessive leakage?

Answer 7

Apply 20 inHg
A drop of 10 inHg in 10 seconds is excessive

201kb pg. 15

Question 8

Should the cylinder head be pulled down onto the block with the fasteners when reinstalling?

Answer 8

No. Could damage the head or gasket.

201kb pg. 17

Question 9

What would result from having oil in the cylinder head bolt holes when installing and torquing the cylinder head down?

Answer 9

Hydraulic lock and potentially crack the block

201kb pg. 17

Question 10

Accuracy of torquing is subject to what 4 factors?

Answer 10

• Thread condition
• Condition & lubrication of mating surfaces
• Type of lubrication used
• Accuracy of the torque wrench

201kb pg. 18

Question 11

Valve clearance adjustments are necessary to:

Answer 11

• Provide clearance for heat expansion
• Compensate for regular wear

201kb pg. 21

Question 12

What position must the valves be in prior to valve clearance adjustments?

Answer 12

Closed, with cam followers on base circle of cam lobe

201kb pg. 22

Question 13

Why must injectors be installed with new o-rings and seals?

Answer 13

To prevent fuel and combustion gas leaks

201kb pg. 23

Question 14

What could result from over compressing valve springs during installation?

Answer 14

Damage to valve seals

Question 15

As the installed height of valve springs increase, valve spring tension:

Answer 15

Decreases

Question 16

Crossheads must be carefully adjusted to ensure that:

Answer 16

Both valves open at precisely the same time