ASE A1 Engine RepairCylinder Head and Valve TrainHard
A technician is reassembling a cylinder head after a valve job. The service manual specifies that the valve springs should be installed with the closer-wound coils towards the cylinder head. What is the primary reason for this specific orientation?
- ATo reduce friction between the spring and the retainer.
- BTo increase valve lift.
- CTo improve oil drainage from the valve spring pocket.
- DTo prevent valve spring surge and resonance.
Show answer & explanationAnswer & explanation
Correct answer: D. To prevent valve spring surge and resonance.
Placing the closer-wound coils (or 'dead coils') against the cylinder head helps to dampen vibrations and prevent valve spring surge (harmonic resonance) at high engine RPM, improving valve train stability and preventing valve float.
Why the other options are wrong
- A. While some friction exists, this is not the primary reason for the specific orientation; the primary concern is spring dynamics.
- B. Valve spring orientation does not affect valve lift; lift is determined by the camshaft lobe.
- C. Oil drainage is typically managed by the cylinder head design and the valve stem seals, not by the orientation of the valve spring coils.
Valve Spring Surge
A phenomenon where valve springs vibrate at their natural frequency, causing uncontrolled valve movement (valve float) at high engine speeds.
- Occurs at high engine RPM.
- Causes uncontrolled valve movement (valve float).
- Dampened by correctly oriented progressive-rate springs.
Memory trick: Tight coils down low, keeps the spring in flow.