ENGINES
AUTO 1-2
Pasco High Auto Shop
1. Engine Block
1. Engine Block
 Metal
foundation
 Supports crankshaft and usually camshaft
made of cast iron or aluminum, aluminum
parts that wear will have metal inserts that
are pressed or cast into the block.
 Cylinder - round hole formed in block
bored and honed to a fine finish, acts as a
guide for piston and a container for the fuel
charge
2. Cylinder Sleeves
 Round
pipe like liners
2. Cylinder Sleeves
 Removable
type or cast into block, wet and
dry sleeves,
 DRY pressed in block supported and
surrounded, its full length - most common
gas engine.
 WET pressed in block supported only at top
and bottom - cooling water comes in direct
contact - heavier construction has sealing
rings
Securing sleeves
 When
cast into block they usually have
grooves in the outside of sleeves to secure it
when pressed in it can have flange on top or
will be held in only by friction of a pressed
fit - head will keep it from coming up.
3. Piston
 Sliding
plunger in cylinder creates vacuum
on intake stroke, compresses mixture on
compression stroke transmits and contains
the pressure of the firing stroke, cleans the
cylinder of burned gases on the exhaust
stroke.
Piston materials
 aluminum
- cast - most common,
 forged- found in hi-performance engines
Expansion of Piston

If the piston is to loose it can cause piston
slap, piston too loose in cylinder tips from
side to side
Old styles of Piston
 split
skirt, skirt closes as piston warms up.
 T slot, same as split skirt but has a T top to
prevent heat of piston head transferring to
skirt
 steel strut, steel cast into aluminum piston
steel expands less then aluminum and helps
reduce expansion
New style
 cam
ground, minimum clearance on thrust
sides egg shaped
 thrust surface, side of piston that is at right
angles to crank shaft and piston pin surface
side that prevents tipping and supports the
piston.
skirts
 full
skirt skirt goes all the way around
piston not cut away.
 slipper skirt, piston skirt cut away below
piston pin for counter weights piston lighter
reduces inertia load on bearings makes
engine more responsive
piston temperature
 head
of piston up to and above 600' F
bottom of skirt about 300'F, head of piston
is .030 to .040 in smaller then skirt to allow
for expansion top can be of different
shapes
Piston Shapes
 flat,
dome, wedge, irregular - to help in
exhausting burned gases
 Piston pin boss, section of piston that
supports piston pin inboard pin boss - most
engines, out board pin boss - performance
and competition
 valve reliefs- small indentations machined
into the top of the piston.
4. Piston rings
3 piece Oil ring
4. Piston rings
 ride
in grooves in piston head to seal the
cylinder
 types of rings, compression - prevent
pressure leakage into the crankcase
 different grooves, bevels, and chamfers
causes internal stress causing scraper action
on downward stroke taking any oil down
that was missed by the oil ring
Piston rings
 firing
pressure forces top ring down for full
face contact
 inner groove usually goes up
 outer groove usually goes down
 material, rings made of cast iron, some are
chrome plated, some are molybdenum
coated or a grooved filled with moly, some
rings are stainless steel
Oil control rings scrape oil off cylinder wall and send pack
to crank case all new sets are three piece
expander and two steel rings some old oil
rings are just one ring break easy.
 compression and oil control rings can have
an expander ring to help force out the ring

Piston ring gap joints, most
common - butt
 lap
and bevel have been used
 some engines have a pin in piston ring
groove to prevent ring from moving
 piston ring gap usually .003-.004 for each
inch of cylinder diameter
Ring Width
 Distance
ring
from the top to the bottom of the
heat dam
 groove
in head of piston that prevents or
lowers the amount of heat transferred to the
top ring
 top ring groove insert, metal insert cast into
aluminum piston with piston groove cut out
of insert to help prolong the life of the
piston
5. Piston Pins
 steel
pin used to connect piston to
connecting rod
 case hardened, soft center .004 outside
hardened highly polished
securing piston pins
 1.
full floating pin, snap ring each end pin
can turn in piston bosses and connecting
rod may have bronze bushing
securing piston pins
 2.
press fit (rod pressed into the
connecting rod) pin turns in aluminum
piston boss.
securing piston pins
 3.
pin locked to rod by bolt not very
common.
6. Connecting Rods
 connect
piston to the crankshaft upper end
oscillates lower or large end rotates lower
end must be split for installation of bearing
and installation on crankshaft journal.
before removing number rod and rod cap on
same side with a number.
6. Connecting Rods
 Steel
Rod
Aluminum Rod
7. Insert Bearings
 removable
bearing split in two pieces for
easy installation and removal
7. Insert Bearings
 steel
back with soft lining, coating can be of
babbitt, copper-lead-tin or aluminum
coating
 locating tabs help keeps insert bearing from
turning
Insert Bearings
 crush
height the .001 to .002 protruding
above rod cap and rod that when bolted
together forms the tight fit that prevents the
bearing from turning.
 An undersize bearing is used on a
crankshaft that has been machined to a
smaller size.
BEARING PERFORMANCE
 load
strength- must withstand pounding
from compression and firing stroke
 anti scuffing - if oil pressure is lost lining
must be soft enough to prevent crankshaft
journal from being scratched or scuffed
 corrosion - must resist corrosion from
vapors and acids in crankcase
 conformation - must conform to shape of
crankshaft journal
BEARING PERFORMANCE
 embedability
- must allow small particles
to embed itself into bearing material so
journal won't be scratched
 temperature - must work equally well both
hot and cold must transfer heat well
 oil hole or groove for lubrication
BEARINGS
 rod
bearings, bearings in the connecting rod
 main bearings, bearings that go where the main
bearing cap hold the crankshaft in place.
THRUST BEARINGS
 thrust
bearing, has sides on to help prevent end play of
crankshaft, sometimes use a separate piece for the side.
8. Crankshaft
Crankshaft, change reciprocating motion to
rotary motion
 made of Forged steel (should ring when
you hit it with a hammer) or cast iron
 counter balances, forged in crank to offset
weight of crankshaft throw

Crankshaft
 crankshaft
throw, the part of crankshaft that
the connecting rod fastens to also refer to as
rod journal
 crank main journal, by use of main bearing
caps crankshaft is bolted to block
 crankshaft is drilled so oil can be fed to
main bearings and rod bearings, crankshafts
are ground and highly polished
9. Harmonic Balancer or
Vibration Damper
 Helps
absorb torsional vibration of
crankshaft and smooth out firing pressure of
each cylinder, 2 pieces with rubber plug or
lining
10. Flywheel
 1.
smooth out engine speed
 2. mounting surface for clutch
 3. starter motor engage ring gear to start
engine
 4. carry engine through power strokes
11. Camshaft
 opens
the valves in engine cam lobes open
the valves one per valve shape of lobe
determines how long valve stays open and
how far it opens also gear to drive the
distributor and oil pump an eccentric may
be ground or bolted onto cam to drive the
fuel pump
12. Timing chain, belt and gears
 drive
chain or belt that connects the
crankshaft gear(driving force) to the cam
shaft gear (the driven force) camshaft turns
at 1/2 crank shaft speed.
 light duty chain, heavy duty - double roller,
driven by all gears, crank gear - steel, cam
gear - steel, aluminum, pressed fiber,
plastic, must be aligned
tensioner for belt or chain
Off of a 96 Olds
chain drive
Off a 75 Toyota 2TC
chain drive
12. Timing chain
12. Timing gears
13. Valves
 device
used to open and close
the valve port, engines have 2
3 or 4 valves per cylinder
 some valves have a special
hard facing on the face
stellite faced valves
Valves
 valve
faces are ground at different angles 2930 and 44-45 most common. interface angle
valve face 44 seat 45, exhaust valve may
climb out of seat
 cooling, heat dissipates through valve seat
and valve guide some valves (heavy duty
truck) are sodium filled to help transfer heat.
CAUTION:
SODIUM, IF DROPPED
INTO WATER WILL BURST
INTO FLAMES WILL CAUSE
SERIOUS BURNS IF IT GETS
ON TO YOUR SKIN.

14. Valve seat
 Part
of head or block that valve face comes
in contact with to seal cylinder. Can be part
of head or an insert that is pressed in. most
now are hardened seats valve seat angle 30
and 45
15. Valve springs
 closes
valve when lifter comes off cam
lobes some valves use 2 springs per valve,
Must measure valve spring installed height,
coil bind - spring can only go together so
far.
16. Valve spring retainer
 holds
spring in place with a valve lock or
keeper
Valve keepers
 holds
lock
valve in place maybe called a stem
Valve Stem seals
 Valve
seals prevent oil from being drawn
into the engine. Deflector seals usually
called Umbrella seals and a Positive seal
are the most common types. GM uses a
O-ring on there engines.
17. Valve guide
 hole
through which valve
passes to keep it in
proper alignment can be
cast into head or pressed
in must have .002 - .003
clearance
18. Valve lifter
 mechanical
- solid
 lifters are solid or hollow
made of cast iron bottom
that contacts camshafts is
hardened adjustment is
taken care of in rocker arms
on most engines some lifters
are adjustable.
Hydraulic Valve lifter
 Hydraulic,
self adjusting has zero valve
lash clearance(No space between parts), use
engine oil under pressure to operate are
quieter then solid lifters operation, may use
flat check valve or ball.
Hydraulic Valve lifter
 Roller
Lifter - has a small roller that rolls
on the camshaft.
19. Lifter guide
 bore
in block that contain lifter has oil
passage in it to supply oil to lifter
20. Rocker Arm
 Transmit
cam lobe action to the valve stem,
two type adjustable and non adjustable can
be mounted on shaft or a individual stud,
overhead cam-rocker arm operates on
camshaft (eliminates the middle man),
roller rockers
20. Rocker Arm
20. Roller Rocker Arm
21. Push rod
 Transmits
valve train motion from valve
lifter to rocker arm
22. valve port
 passages
which allow the air fuel mixture in
and the burned fuel out
23. Crank case or oil pan
 reservoir
for oil usually made of stamped
steel attached to the bottom of block the oil
pump is usually with in this reservoir
The
End
Scott
Salisbury