Exam 12: Upper-End Theory and Service

To protect against scuffing and wear, some valves have coatings of black nitride applied to the valve stem.

What happens when valve spring tension is too low?

While disassembling a cylinder head, what would indicate that the valve seals are worn or damaged?

Technician A says VVT (variable valve timing)engines use a cam phaser that advances or retards the camshaft as the engine is running. Technician B says VVT engines use a third cam lobe with increased lift and duration, operating a third rocker arm that is coupled to the two primary rocker arms by a hydraulically controlled pin, while the engine is running. Who is correct?

The hemispherical combustion chamber provides excellent turbulence to the air and fuel mixture.

Technician A says the end of the valve spring that is wound the tightest should face toward the spring retainer. Technician B says the O-ring seal should be installed in the lowest of the keeper grooves on the valve stem.

Aluminum cylinder head bolts should never be loosened or tightened when the metal is hot.

A single hole in the cylinder head that divides into two branches is called a _____ port.

Technician A says positive valve stem seals fit loosely around the top of the stem. Technician B says positive stem seals scrape oil off the valve as it moves up and down. Who is correct?

The distance between the valve face and the head of the valve is called the ____________________.

_____type valve stem seals move up and down with the valve stems to deflect oil away from the guides.

Prussian blue or machinist dye is used to ______.

Sodium-filled valves should be cut open for inspection.

Aluminum cylinder heads weigh roughly half as much as cast-iron heads.

In response to temperature changes, aluminum expands and contracts almost twice as much as cast iron.

Stainless steel is nonmagnetic.

Resurfacing the cylinder head can affect _____.

Installed valve spring height can be adjusted with ____________________.

____________________ support the valve in the head and prevent the valve from moving in any direction other than up and down.

Technician A resurfaces valve seats using a grinding stone. Technician B resurfaces valve seats using a cutting blade. Who is correct?