Cylinder Head and Valve Train Module Flashcards
What is the purposes of a camshaft?(2)
-Changes rotary motion to reciprocating motion
-Controls opening and closing of intake and exhaust valves
2 types of cam arrangements
Cam in block
Over head cam
True or False;
The camshaft gear is smaller than the crankshaft gear on a four stroke engine.
False - because it rotates slower
The 4 components in a valve train.
Camshaft
Lifter
Push Rod
Rocker Arm
What speed does the camshaft rotate in relation to the crankshaft on a 4 stroke engine?
Camshaft rotates at 1/2 the speed of the crankshaft.
3 types of cam followers;
Solid
Roller
Hydraulic
What keeps the camshaft timed with the crankshaft?
Gears, Chain, or Timing Belt
True or False;
Pushrods may have hollow tubes with oil galleries so oil can be sent to the cylinder head.
True
Which valve train component makes up the mechanical link between the pushrod and valve?
Rocker Arm
What is the purpose of the cylinder head ports?
The cylinder head ports direct flow in and out of the cylinders
3 main functions of the cylinder head.
-Retains gasket seal between head + block
-Contains combustion chamber, valves, oil and coolant galleries
-Houses manifolds and injectors, air start and gas admission valves
2 basic functions of valves are;
-Seals cylinder during compression and power events
-Permits air/fuel mix on intake, removes combustion gases on exhaust
Why is an exhaust valve usually made of higher quality materials than an intake valve?
-Operates at higher temperatures
-Subject to corrosive gases flowing through
On a solid stem valve, the majority of the cooling takes place at the;
Valve face and Valve Seat
When compared to an integral valve seat, valve seat inserts provide a replaceable wear surface with improved….
Wear characteristics
Valve seals control valve guide and stem lubrication to prevent;
Oil consumption
Before removing the cylinder head from a locked out and purged engine, you must do what task first?
Drain the oil and coolant
After replacing valves and valve seat inserts, you should always check;
Valve face and valve seat contact
Which valve type usually requires more clearance and why?
Exhaust valve
-high exhaust gas temperatures flowing through the valve and valve seat.
True or False;
When adjusting valve lash using the firing order of an engine, the piston should be positioned at TDC and in the compression stroke with both valves closed for that cylinder.
True
What type of lever is a rocker arm?
Class 1 lever
What do valve seals do?
Control lubrication of the valve guide and stem
-bad valve seals, blue smoke on initial acceleration.
