Ford Thunderbird 1958 User Manual

PART 1-ENGINE
1-13
When
compressing
the
valve
spring
to
remove
push
rods,
be
sure
the pis
ton
in
the
individual
cylinder
is
be
low
T.D.C.
to
avoid
contact
between
the
valve
and
the
piston
or
serious
damage
could
result.
To
replace a
push
rod,
it
will be
necessary
to
remove
the
valve
rock
er
arm
shaft
assembly
as
outlined on
page
1-16,
step
2.
Upon
replacement of a
valve
push
rod
and/or
valve
rocker
aim shaft
assembly,
the
engine
should
not
be
cranked
or
rotated
until the
hydraulic
lifters
have
had
an
opportunity
to
leak
down
to
their
normal
operating
position.
The
leak
down
rate
can be
accelerated
by
using
the
tool shown
in Fig.
13
on
the valve
rocker
arm
applying
pressure
in a
direction
to
collapse
the
lifter.
MANIFOLD
VACUUM
TEST
A
manifold
vacuum
test aids in
determining
the
condition of an
en
gine
and
also in
helping
to
locate
the
cause
of
poor
engine
performance.
To
test
manifold
vacuum:
1.
Operate the
engine
for a
mini
mum
of
Vi-hour
at
1200
rpm.
2.
Install an
accurate,
sensitive
vacuum
gauge
on the
fuel
pump
end
of
the fuel
pump
vacuum
line.
3.
Operate the engine at recom
mended idle rpm.
4. Check
the
vacuum
reading
on
the
gauge.
TEST
CONCLUSIONS
Manifold
vacuum
is
affected
by
carburetor
adjustment,
valve
timing,
the condition
of
the
valves,
cylinder
compression,
and
leakage
of the
manifold,
carburetor,
or cylinder
head
gaskets.
Because abnormal
gauge
readings
may
indicate
that more than one of
the
above factors is
at
fault,
exercise
caution in
analyzing
an
abnormal
reading.
For
example,
if
the vacuum
is
low,
the
correction of
one item
may
increase
the
vacuum
enough
so
as
to indicate that
the
trouble has
been
corrected. It
is
important,
there
fore,
that
each cause of an
abnormal
reading
be
investigated
and
further
tests
conducted
where
necessary
in
order to arrive
at
the correct
diag
nosis
of the
trouble.
Table
4
lists
various
types of
read
ings and
their possible
causes.
This
table
is
merely
a
guide,
however,
and
not a firm
standard.
Allowance
should be
made
for the
affect of
altitude on
the
gauge read
ing.
The
engine
vacuum
will decrease
with an
increase in
altitude.
TABLE
4
Manifold Vacuum Gauge
Readings
Gauge
Reading
Engine
Condition
19-20
inches.
Normal.
Low
and
steady.
Loss
of
power
in
all
cylinders
caused
possibly
by
late
ignition or
valve
timing,
or loss
of
compression due
to
leakage
around the
piston
rings.
Very
low.
Manifold, carburetor,
or
cylinder
head
gasket
leak.
Needle fluctuates
steadily
as
speed increases.
A
partial or complete
loss of
power
in
one
or
more
cylinders
caused
by
a
leaking
valve,
cylinder
head
or
intake
manifold
gasket
leak,
a defect
in the
ignition
system,
or a
weak
valve
spring.
Gradual
drop
in
reading
at
engine
idle.
Excessive back
pressure in
the
exhaust
sys
tem.
Intermittent fluctuation.
An occasional loss of
power
possibly
caused
by
a
defect in the
ignition
system
or a stick
ing
valve.
Slow
fluctuation or
drifting
of
the
needle.
Improper
idle
mixture
adjustment,
carbu
retor
or intake
manifold
gasket
leak,
or
pos
sibly
late valve
timing.
ENGINE COMPRESSION TEST
1. Be
sure the
battery
is
good.
Operate
the
engine for a
minimum
of
Vi
hour
at 1200
rpm. Turn the
ignition
switch
off,
then
remove
all
the spark
plugs.
2.
Set
the
primary
throttle plates
and
the choke
plate in
the wide open
position.
3.
Install a
compression
gauge
in
No.
1 cylinder.
4.
Crank
the
engine until
the
gauge
registers a
maximum
reading
and
record the
reading.
Note
the
number
of
compression
strokes
re
quired to
obtain
the
maximum
read
ing.
5.
Repeat
the test
on each
cylinder,
cranking
the
engine
the
same number
of
strokes for
each
cylinder as
was
required to
obtain a
maximum read
ing
on No. 1
cylinder.
TEST
CONCLUSIONS
A
variation of
20
pounds
from
specified
pressure
is
satisfactory.
However,
the
compression
of
all
cyl
inders
should
be
uniform
within 10
pounds.
A
reading
of
more than 20
pounds
above
normal indicates
excessive de
posits
in the cylinder.
A
reading
of
more than 20
pounds
below
normal
indicates
leakage at
the cylinder
head
gasket,
piston
rings,
or valves.
A
low
even
compression in
two
adjacent
cylinders
indicates a
cyl
inder
head gasket leak.
This
should
be checked
before
condemning
the
rings
or
valves.
To determine whether
the rings
or
the
valves
are at
fault,
squirt
the
equivalent
of a
tablespoon of
heavy
oil
in
the
combustion
chamber,
then
crank
the
engine to
distribute
the oil
and
repeat
the
compression
test.
The
oil will
temporarily
seal
leakage
past
the rings.
If
approximately
the
same
reading
is
obtained,
the
rings
are
sat
isfactory,
but
the
valves
are
leaking.
If
the
compression
has
increased
10
pounds
or
more
over
the
original
reading,
there is
leakage
past
the
rings.
During
a
compression
test,
if
the
pressure
fails
to
climb
steadily
and
remains
the
same
during
the
first
two
successive
strokes,
but
climbs
higher
on
the
succeeding
strokes,
or
fails
to
climb
during
the
entire
test,
it
indi
cates
a
sticking
or
stuck
valve.

Ford Thunderbird 1958 Specifications

General

Brand	Ford
Model	Thunderbird 1958
Category	Automobile
Language	English