AERA Cylinder Head Rebuilding & Valve Train 3

Question 1

What is the purpose of measuring valve stem runout (stem straightness) before reusing a valve?

Accepted Answer

A bent stem causes guide wear, side loading on the seat, and erratic valve sealing

Answer

Stem runout determines whether a larger oversize stem diameter is needed

Answer

It confirms the valve head is concentric with the combustion chamber

Answer

Runout measurement replaces the need to check valve face condition

Question 2

On a hydraulic roller lifter engine, what is the specified preload range typically applied to the lifter after zero lash is established?

Accepted Answer

1/4 to 3/4 turn past zero lash

Answer

2 to 3 full turns past zero lash

Answer

Zero lash with no additional preload

Answer

1/8 turn before zero lash (slight slack)

Question 3

Which type of valve spring design is most resistant to harmonic surge at high engine speeds?

Accepted Answer

Variable-pitch (beehive or dual) spring

Answer

Single-coil constant-pitch spring

Answer

Solid damper insert inside a standard spring

Answer

Flat wire wound single spring

Question 4

What condition does a valve spring tester measure, and at what point is a spring considered unserviceable?

Accepted Answer

It measures spring pressure at a specified compressed height; a spring is unserviceable if pressure is more than 10% below spec

Answer

It measures free length only; replace if less than 5% under spec

Answer

It measures coil bind height; replace if the spring binds before maximum lift

Answer

It measures spring rate in lb/in; replace if rate varies more than 5% between springs

Question 5

When installing valve keepers (locks) in a cylinder head, what tool-related practice prevents them from unseating during assembly?

Accepted Answer

Apply a small amount of assembly grease to the keeper grooves to hold them in place while the spring compressor is released

Answer

Use an air hammer to seat the keepers firmly before releasing the spring compressor

Answer

Install keepers only after torquing the cylinder head to the block

Answer

Heat the retainer to expand it before installing keepers for easier assembly

Question 6

An engine is found to have excessive valve guide clearance. Which repair method restores OEM-equivalent performance while also allowing for future service?

Accepted Answer

Install a thin-wall bronze guide liner (Knurling is only a temporary fix)

Answer

Knurl the existing guide to raise metal and reduce clearance

Answer

Install a valve with an oversized stem diameter

Answer

Apply a hard chrome coating to the valve stem to take up clearance

Question 7

What is the purpose of the valve rotator (Roto-cap) fitted to some exhaust valves?

Accepted Answer

To slowly rotate the valve each time it opens, distributing wear and preventing carbon buildup on the seat

Answer

To lock the valve in a fixed rotational position to ensure consistent seat contact

Answer

To reduce valve spring pressure requirements by converting spring energy to rotation

Answer

To increase valve lift by leveraging rotational momentum