Valve Guide Reaming
- Measure the valve stem to guide clearance.
- Using a micrometer (1) measure the diameter of the valve stem (a).
- Using a ball style measuring gauge, measure the inner diameter (b) of the valve guide at the specified depth. Refer to Engine Mechanical Specifications (LS7) .
- Subtract the valve stem diameter (a) from the valve guide inner diameter (b) to obtain the valve stem to guide clearance.
- If the clearance measurement between the valve stem and guide is not within specification, the valve and/or the cylinder head must be replaced. Refer to Engine Mechanical Specifications (LS7) .
- Inspect the valve stems for excessive scoring, wear, or warpage.
- A valve stem that has excessive scoring (3 or 4) or wear (4 or 6) must be replaced.
- If a valve guide is worn or has excessive stem-to-guide clearance, the cylinder head should be replaced.
- Measure the valve stem diameter. If the valve stem diameter is not within specification, the valve must be replaced. Refer to Engine Mechanical Specifications (LS7)
.
If the valve stem diameter is within specifications, and the stem-to-guide clearance is excessive, the cylinder head must be replaced.
Do not clean titanium components with chlorinated solvents. Brake parts, and similar cleaning solvents, safety solvents, or refrigerant that contains chlorofluorocarbons (CFCs) should not be used. Using chlorinated solvents to clean titanium components can result in component damage, leading to stress corrosion cracking that may be undetected with normal visual inspection. Acceptable materials for cleaning titanium components include non-chlorinated solvents, alcohol, acetone, and methanol.
Excessive valve stem-to-guide clearance may cause a noisy valve train, premature valve stem oil seal wear, component damage, and/or excessive engine oil consumption.
Insufficient valve stem-to-guide clearance will result in noisy or sticking valves. Valves that are too tight may disturb engine smoothness or lead to component damage.