J- Cylinder Head Fundamentals

Explain the purpose of cylinder head ports

Direct airflow in and out of the cylinder

Explain the purpose of a coolant directional nozzle

Direct coolant flow to critical areas of the cylinder head

List two types of valve guides

Integral and Removable

Explain the purpose of a valve bridge (crosshead)

It spans a pair of intake or exhaust valves and allows one rocker arm to open both valves simultaneously

A valve spring seat is used to

Prevent erosion of the cylinder head where the spring contacts the casting

Explain the purpose of a valve spring

Provide the necessary force to keep the valve face in contact with the seat to seal the combustion chamber. Also controls valve oscillations and keep the cam follower in contact with the cam lobe as engine RPM increases

List two reasons why there must be a seal between the cylinder head and an injector tube

To prevent coolant from leaking past the tube into the combustion chamber and crankcase, and combustion from leaking past the tube into the cooling system

list the two advantages of a sodium-cooled valve

additional cooling between valve stem and valve guide and 15% cooler than a solid stem valve

List two advantages of using cap screws to retain the cylinder head

an efficient method for the installation and removal of cylinder heads, and clear access to the cylinder block deck and cylinder liner after cylinder head removal

Depending on engine design the cylinder head may cover

any amount of cylinders

The most common material used for diesel engine cylinder head construction is:

cast iron alloy

Steel head gaskets have a high degree of strength but lack (blank)

conformability

The overhead camshaft design

eliminates the need for a pushrod

The purpose of a carbon scraper on a valve it to prevent carbon buildup

in the lower part of the valve guide

briefly explain why an exhaust valve is usually made of higher quality material than an intake valve

it operates with higher temperatures and corrosive gases

valve seals control valve guide and stem lubrication to prevent:

oil consumption

List the two benefits of having valves equipped with rotators

provides a changing wear surface for more even valve/seat wear and creates a wiping action that helps keep the valve face and seat clean of carbon

List the components of the valve operating mechanism for an engine with camshaft in the cylinder block

rocker shaft, rocker arm, support (pedestal) push rod, cam follower, cam lobe

The purpose of the coolant and oil passages in the cylinder head is to

route coolant and oil to the cylinder head and its components

List the two basic functions of valves

seal the cylinder during compression and power events and open and close the cylinder to allow airflow during the intake and exhaust events

List two types of head gasket construction

steel and compositionk

Explain the purpose of valve locks

they locate the retainer during assembly and keep it in position

What is true about cylinder head retaining studs?

they provide a higher clamping force than cap screws

Explain the purpose of the hole drilled through the centre of a rocker shaft

to allow lubrication of the rocker arm assembly

Explain why pushrods are most often made of tubular steel

to reduce the weight of the operating mechanism

On a solid stem valve, the majority of cooling takes place between the (blank) and the (blank)

valve face and valve seat

list the two main benefits of a four-valve cylinder head (as compared to a two-valve cylinder head)

volumetric efficiency and turbulence

When compared to an integral valve seat, valve seat inserts provide a replaceable wear surface with improved:

wear characteristics and heat resistance