Exam 12: Upper End Theory and Service

Technician A says multivalve engines can have three valves per cylinder. Technician B says multivalve engines can have five valves per cylinder. Who is correct?

Why does a properly finished valve seat have three different angles?

How does refinishing a valve face and the valve seat affect its position in the cylinder head?

Aluminum expands and contracts almost twice as much as cast iron in response to temperature changes.

Technician A says heat is transferred from an exhaust valve to the cylinder head through the valve seat. Technician B says some exhaust valves have a hollow stem filled with silicone to transfer heat to the valve guide. Who is correct?

Valve stem wear may be measured with a ____________________.

Where on the cylinder head are cracks most likely to occur?

Powder metal valve seats are softer and do not last as long as cast iron seats.

Technician A says worn valve stem seals can increase oil consumption. Technician B says worn valve stem seals can cause valve deposits. Who is correct?

Resurfacing the cylinder head can affect _____.

What happens when valve spring tension is too low?

Sodium-filled valves should be cut open for inspection.

The surface of a valve that comes into contact with the valve seat is called the valve ____________________.

Technician A says positive valve stem seals fit tightly 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?

Valve guides are _____.

Technician A says if valve stem height exceeds specifications, it can be adjusted by grinding the valve tip. Technician B says the valve stem height can be adjusted with shims. Who is correct?

Resurfacing a cylinder head gasket surface may alter the combustion chamber volume.

Technician A checks for bent pushrods by rolling them on a flat surface. Technician B checks for bent pushrods using a dial indicator and V-blocks. Who is correct?

Describe a hemispherical combustion chamber.

A cylinder head may be made of cast iron or aluminum.