Engine notes

cypriotcamelUrban and Civil

Nov 29, 2013 (3 years and 10 months ago)

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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 from the top to the bottom of the
ring

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 29
-
30 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 valve in place maybe called a stem
lock

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