Filter
Top Products
20
Engine
Tractors,
Lawn
and
Garden
-
110
and
112
35-8
PistOll,
Crankshaft
and
Flywhee
l - T
ec
umseh
SM
-2
05
9-
(Apr-
67)
P
ISTON
ANALYSIS
Fig.
IB-Piston
Top
Land
Burning
Caused
by
De/ona/ion
Detonation
is
a
form
of
abnormal
combustion
causing
excessive
temperature
and
pressure
in
the
combustion
chamber.
Commonly
called
car-
bon
knock,
spark
knock
or
timing
knock,
deto-
nation
occurs
as
compressed
air-fuel
mixture
ignites
spontaneously
to
interrupt
the
normal
ignition
flame
front.
When
detonation
is
detected,
check
and
correct
the
following
possible
causes:
1.
Lean
fuel
mixtures.
2.
Low
octane
fuels.
3.
Over-advanced
ignition
timing.
4.
Engine
lugging.
5.
Build-up
of
carbon
deposits
on
piston
and
cylinder
head
causing
excessive
compression.
6.
Wrong
cylinder
head
or
milling
of
head
increasing
compression
ratio.
Fig.
19-Hole
Burned
in
Piston
Caus(!d
by
Pre.lgnition
Pre-ignition
is
the
igniting
of
the
fuel-air
mixture
prior
to
the
regular
ignition
spark.
Pre-
ig"nition
causes
severe
internal
shock
resulting
in
pings,
vibration,
detonation
and
power
loss.
Severe
damage
to
piston,
rings
and
valves
resu
lt
s
from
pre-ignition.
When
pre-ignition
is
suspected
and
de
te
cte
d,
check
and
correct
the
following
possible
caus
es:
1.
Internal
carbon
depOSits
which
remain
incandescent.
2.
Incorrect
spark
plug
(high
heat
ran
a"e).
3.
Broken
ceramic
in
spark
plug.
4.
Sharp
edges
on
valves
or
elsewhere
in
the
combustion
chamber.
Litho
in
U.S.A.