Engine component
Transcript of Engine component
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ENGINE TOP END
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Types of Cylinder Heads
Old fashion
Flatheads
Overhead Valve(OHV or I-Head)
Single Overhead
Cam (SOHC)
Dual Overhead Cam
(DOHC or Twin
cam)
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Flathead EnginesAll valve train parts are in the
cylinder block.Cylinder heads have nothingmore than water jackets,spark plug threaded hole andsome bolt holes.
Tend to be very lowcompression. Poor power bytodays standards.
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VALVE TRAIN
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VALVE TRAIN
CONSTRUCTIONValve construction
Valve seal construction
Valve spring construction
Valve spring shim
Valve retainers and keepers
Valve spring seatValve rotators
Valve stem cap
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Valve Train Components
Valve train
components will
vary depending onthe type of head
configuration.
OHV, SOHC or
DOHC
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Overhead Valve EnginesHas valves in cylinder
head increasing
compression.
Camshaft still in block.Uses lifters, pushrods
and rocker arms.
Most common head
design until 1990s.
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Single Overhead Cam
(OHC)/(SOHC)Single cam mountedin head.
Opens both intake
and exhaust valves.
One cam on an
inline engine and
two cams on a veeengine.
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Dual Overhead Cam (DOHC)
Camshafts mounted incylinder head.
One cam opens intakevalves and one opens
exhaust valves.Often used with 4valves per cylinder.
Most high performanceof all types.
Vee engines have 4cams.
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DOHC
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Camshafts
Opens the valves at the
right time.Actually converts rotarymotion to reciprocatingmotion.
Uses a cam lobe for eachvalve.
Usually made of cast iron.
Has a great effect on
engine performance.Can be given auxiliaryfunctions like running theoil pump or distributor.
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CAMSHAFT
CONSTRUCTIONCam lobes
Camshaft thrust
plateCam bearings
Cam housing and
cam cover
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Cam Lobe TerminologyHeel as known as
the base circle.
Nose is the tip of
the lobe which
determines cam lift.
Opening and
closing flanks andramps.
Timing points are
where the cam
starts to open andclose the valve.
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Cam Lobe LiftThe distance thevalve is pushed
open.
It is determined bythe height of the
lobe.
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Cam Duration
This chart is indegrees ofcrankshaft rotation.
Note when the
valves open andclose and on whichstrokes. This is theduration.
Its not what it mayseem to be!
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Camshaft DrivesGear on gear
Gear and chainBelt and notchedpulley
Cam gear ALWAYS
is twice as large asthe crank gear, thismakes the cam turn
at thespeed of the crank.
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Gear to Gear Drive
Simplest drive
system.
Reliable and strongbut noisy.
Reverses Direction
of Power 2 times
CW>CCW>CW
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Gear and Chain Drive
Quieter the gear
types.
Allows cam to befurther away from
crankshaft.
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Timing Belt
Used primarily onoverhead cam engines.
Uses a kevlar belt. (police vests)
Can snap or stretchcausing catastrophicdamage to non-freerunning engines.
Chains remain morepopular with enginemakers.
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Installing Timing Chains
Look for the timing
marks on the gears.
Point the marks ateach other 6 and 12
oclock.
Install cam gear to
camshaft.
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OHC
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OHC direct
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OHC intermittent Shaft
Intermittent Shaft
drives distributor
Must Align ALL (3)Timing marks!
Belt tension pulley
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Timing Variations
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VALVE &CAMSHAFT
PLACEMENTOHC / SOHCOHV
DOHC
In Block
I
T
VALVE OPERATION
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VALVE OPERATION
http://www.howstuffworks.com/engine-cam.htm
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VALVE LIFTERS
Solid Lifters
Roller Lifters
Hydraulic LiftersFollowers
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SOLID LIFTERS
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ROLLER LIFTERS
HYDRAULIC LIFTERS
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HYDRAULIC LIFTERS
FOLLOWERS
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FOLLOWERS
ohc
V l Lift T i l
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Valve Lifter Terminology
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Valve Lifters
Also known as cam
followers or tappets.
Come in threetypes: ****
Mechanical or solid.
Hydraulic.
Roller (which can be
hydraulic or solid).
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PUSH ROD
CONSTRUCTIONHollow tube
Steel
Vary in lengthFit between Lifter
and rocker arm
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PushrodsMetal rod which transfers force from the lifter to the
rocker arm.
ROCKER ARM
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ROCKER ARM
CONSTRUCTION
Rocker Arms
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Rocker Arms
Rocker arms are
made of stamped
steel, cast iron or
aluminum.
They transmit the
force of the pushrod
to the valve.Some have
adjusters.
Rocker Arms
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Rocker ArmsRoller- Stamped
Stamped
CastAdjuster
Pivot
V l
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Valves
Called mushroom or
poppet valves.
Made of high quality
steel.
The exhaust valve has
one of the toughest jobs
in the engine having to
withstand temperaturesof 1300 degrees F.
Valve Overlap
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Valve Overlap
This is when the
intake and exhaust
valve are open atthe same time.
It doesnt seem right
but it works.
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INTAKE MANIFOLD
CONSTRUCTIONVariable induction
system
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EXHAUST MANIFOLD
CONSTRUCTIONSingle Exhaust
Dual Exhaust
Single w/crossoverHeaders