1953 JEEP DJ length

HURRICANE
F4
ENGINE

FIG.
D-28-
CHECKING
OIL
PUMP
ROTORS

FIG.
D-29—CHECKING OUTER ROTOR
TO
OIL
PUMP
BODY If,
however, the
teeth
are broken, cracked, or
seriously
burred,
the ring gear should be replaced.

D-69.
Ring
Gear
Replacement

The
ring
gear
is secured on the flywheel by a
shrink

fit. Before starting the operation of replacing the
ring
gear, place the new ring gear against the old
gear to make certain both have the same number of
teeth.

To
remove the ring gear from the flywheel,
drill
a [9,5 mm.]
hole
through the ring gear and cut
through any remaining metal with a cold chisel. Remove the ring gear from the flywheel. Thorough-
FIG.
D-30—CHECKING
OIL
PUMP
COVER
ly
clean the ring gear surface of the flywheel. Heat
the new ring gear evenly to a range of
650°F.
to
700°F.
[343°C.
a
371°C.]
and place it on the cold
flywheel,
making
certain that the chamfer on the
teeth
is on the crankshaft side of the flywheel. Be

sure
that the ring gear is firmly seated on the fly­
wheel. Allow the ring gear to cool slowly to
shrink
it
onto
the flywheel. Do not quench the ring gear;
allow it to slowly air cool.

D-7Q.
Flywheel Pilot Bushing

Inspect
the flywheel pilot bushing in the flywheel.

For
procedure on replacing the bushing, refer to

Par.
1-8.

D-71.
Flywheel Housing

The
flywheel housing, which
encloses
the flywheel

and
clutch is bolted to the
engine
rear
plate and
cylinder
block. The
rear
of the housing provides
the front support for the transmission. Examine the housing for cracks and distortion of the

machined
surfaces. The front face must seat evenly
against the
engine
rear
end plate without evidence
of warpage. The
rear
face must be parallel to the front face. Improper alignment may cause trans­mission gear disengagement. In addition, the open­
ing in the
rear
of the housing, which serves as a
pilot for the transmission, must be concentric with the crankshaft. The flywheel housing should be
checked for alignment after it is installed on the
engine. Refer to Par. D-88.

D-72.
Core Hole Expansion Plug

Any
evidence of coolant leakage around any of
the core
hole
expansion plugs
will
require replace­ ment of the plug. The expansion plug at the
rear

end of the cylinder block can be driven out with a 24" [60 cm.] length of half-inch bar stock carefully
inserted through the camshaft bore in the cylinder
block. The other core
hole
expansion plugs in the
cylinder
block and cylinder head can be removed
by piercing the center with a sharp tool and prying them out. Before attempting to install a new plug,
clean
the
hole
thoroughly. Apply a thin coat of
sealer on the new plug and install the plug with a
driver.
60

'Jeep'
UNIVERSAL
SERIES SERVICE
MANUAL

FIG.
D-31
—
CYLINDER

HEAD

1—
Rocker
Arm
Cover

2—
Gasket

3—
Cover
Stud

4—
Connector
5—
Pipe
Plug

6—
Cylinder
Head

7—
Gasket

8—
Pipe
Plug
H'

9—
Thermostat

10—
Gasket
11—
Water
Outlet
Fitting

12—
Screw
and
Lock
Washer

13—
Carburetor
Mounting
Stud

14—
Pipe
Plug
H"
15—
Crankcase
Vent
14413
D-73.
Cylinder Head

Be
sure that water
passages
are
open
and that

all
carbon is removed. Inspect all tapped
openings.
Repair
any damaged threads or broken studs. Run

a
tap in the threaded
holes
to clean up rough or
damaged threads. Before using a tap, squirt penetrating oil on the threads.
Discard
or repair

cracked
cylinder heads, also
those
warped .010"
[0,254
mm.] or more over the
full
length of the head.

The
right side of the cylinder head has an
elbow

screwed
into
the intake manifold which mounts the
crankcase
ventilation valve. Refer to Par. D-l5

and
Fig. D-32 for removal of the valve and
elbow.
13342

FIG.
D-32—CRANKCASE VENTILATION
VALVE

1—Ventilation
Valve
2—90*
Elbow
3—Cylinder
Head
D-74.
Rocker Arms

The
rocker arms and their related parts are
mounted on the top of the cylinder head and en­
closed by the rocker arm cover. The rocker arm
shaft, supported in four rocker arm shaft brackets,
carries
the rocker arms and the rocker arm shaft

springs.
The intake valve adjusting screws and
locknuts provide the means for adjusting
these
valves.
D-75.
Rocker
Arm
Shaft Disassembly

a.
Remove the two studs in the rocker arm shaft
brackets
at the
ends
of the rocker arm shaft.

b.
Slide the rocker arm shaft brackets, the four

rocker
arm assemblies, and the two rocker arm
shaft springs off the rocker arm shaft. Remove the
two rocker arm shaft lock screws from the two re­
maining
rocker arm shaft brackets and slide the

brackets
off the shaft.

c.
Insert a screwdriver under the
edge
of the

rocker
arm shaft plugs at each end of the rocker

arm
shaft, and pry the plugs out of the shaft. 61

D
HURRICANE
F4
ENGINE d.
Remove the intake valve adjusting screw lock-
nuts from each of the rocker arm valve lash ad­

justing
screws. Remove the screws from the rocker
arms.

D-76.
Inspection and
Repair

Run
a round wire brush through the bore of the

rocker
arm shaft and clean out the drilled oil holes.
Clean
out the oil
holes
in the rocker arm shaft

brackets,
and the oil
holes
and
grooves
in the bores
of the rocker arm.
Inspect
the diameter of the shaft at the rocker arm

bearing
areas. Replace the shaft if there are scores

or
abrasion marks along the length of the shaft.
Check
the shaft for alignment by rolling it across

a
smooth level surface. If the shaft
will
not
roll
freely, or if it rolls with a bumping motion, the
shaft is out of alignment and must be replaced.
Inspect
the threads of the adjusting screw
hole
in
the rocker arms and if necessary clean with a

proper
size tap. Replace the adjusting screw lock-
nut or the adjusting screw if either part is damaged

or
deformed.

Inspect
the threads in the tapped
hole
in the top
of the rocker arm shaft brackets and if necessary

clean
with a proper size tap. Replace the bracket

if
either side is worn or scored.

D-77.
Reassembly

a.
Install
two rocker arm shaft plugs, one in each
end of the shaft. Slide two
rocker
arm
shaft brackets
onto
the center of the shaft. Align the tapped
holes

in
the brackets with the drilled
holes
in the top of
the shaft and install the rocker arm shaft lock
screws,
making sure the points of the screws enter
the drilled
holes
in the shaft.

b.
Screw the intake valve adjusting screws into
the rocker arms and install the locknuts.

c.
The rocker arms are paired; that is, two of the
arms
are angled to the right and two are angled to
the left. One of each type is used on each end of
the rocker arm shaft. Slide a rocker arm with the

adjusting
screw end of the rocker arm angling

away
from the bracket
onto
the shaft so that the
adjusting
screw is on the same side of the shaft
as the mounting
hole
in the bracket.

d.
Temporarily
secure the end bracket in place by
installing
a rocker arm cover stud in the tapped
opening in the top of the support.
e. Assemble the parts on the
opposite
end of the
rocker
arm shaft repeating
steps
c and d above.

D-78. ENGINE REASSEMBLY
The
engine
reassembly procedure in the following

paragraphs
is given in the sequence to be followed
when the
engine
is being completely overhauled.
Individual
inspection,
repair,
and fitting operations
previously covered in detail are made throughout
the reassembly procedure. The reassembly pro­
cedure
does
not cover accessories. If a new cylinder

block
fitted with pistons is used, many of the
operations
will
not be required.
Mount
the cylinder block in an
engine
repair stand.
If
an
engine
stand is not available, perform the fol­
lowing reassembly operation in a manner designed to protect personnel against an accident and the

engine
and its parts against damage.

Note:
During
engine
reassembly, use Perfect Seal

Aerosol
Spray
Sealer
Part
No.
994757
on all
engine
gaskets to ensure against vacuum, oil, gasoline and

water
leaks. Apply to head gaskets, valve covers,
water
pumps, oil pan gaskets, radiator and heater
hose
connections, felt gaskets, gasoline and oil line
connections, stud bolts,
spark
plug threads, and
grease retainer washers. Refer to manufacturer's in­
structions on container for proper application pro­
cedure.

D-79.
Install
Oil
Gallery
Plug

Coat
plug threads with a suitable sealing compound

and
install the plugs in the front and
rear
ends of
the oil gallery in the cylinder block and the
rear

end of the cylinder head. Torque the plugs 20 to 25 lb-ft. [2,8 a 3,4 kg-m.].

There
is also a pipe plug
(}/g,f
[3,2 mm.] slotted, headless) in the opening in the main oil gallery inside the cylinder block at No. 2 cylinder and another pipe plug
(}/g
"
square-head) in the opening

in
the oil passage directly below the oil pump intake
passage. If
these
two pipe plugs were removed,
make
certain they are reinstalled in the locations
described above or the counterweight of the

crankshaft
might strike the projecting head of the
square-head
plug.

D-80.
Install
Tappets

Turn
the block upside down. Beginning at the

rear
end of the cylinder block, install the intake

and
exhaust valve tappets in the tappet bores in the cylinder block in the following order: one
exhaust, two intake, two exhaust, two intake, and
finally
one exhaust valve tappet.

Check
the tappet to bore fit of each tappet as it
is installed in the block. If the stem-to-block

clearance
tolerance of .0005" to .002" [0,0127 a
0,051 mm.] is
exceeded
install a new tappet fitting
within
this tolerance or ream the bore to accomo­ date the next oversize tappet which is available

in
.004" oversize.

D-81.
Install
Camshaft and
Thrust
Plate

Lubricate
all camshaft bearings and cam surfaces generously with clean, light
engine
oil.
Carefully,

so not to damage or score the camshaft front bear­
ing,
install the camshaft, locating it properly in the bearings. Do not allow the
rear
end of the cam­shaft to strike sharply against the expansion plug

installed
in the
rear
end of the bore.
Install
the camshaft thrust plate. Slide the thrust
plate spacer
onto
the end of the camshaft with the
beveled inner
edge
of the spacer facing the cam­
shaft. If the same camshaft is being reinstalled,
install
any shims previously removed. These shims
are
placed
between
the camshaft shoulder and the

spacer.
Torque the thrust plate attaching
bolts
20
to 26 lb-ft. [2,8 a 3,6 kg-m.].

End
play of the camshaft is determined by running
clearance
between
the
rear
face of the camshaft
gear and the thrust plate. The standard clearance 62

D
HURRICANE
F4
ENGINE

FIG.
D-34—GAUGING
CRANKSHAFT
END
PLAY
FIG.
D-35
—
DRILLING FLYWHEEL
D-84.
Install
Crankshaft Timing
Gear

Install
the woodruff key in the longer of the two keyways on the front end of the crankshaft.
Install

the crankshaft timing gear on the front end of the crankshaft with the timing
mark
facing out, away from the cylinder block. Align the
keyway in the gear with the woodruff key and then

drive
or press the gear
onto
the crankshaft firmly against the thrust washer.

D-85.
Install
Crankshaft
Rear
Bearing Seal

When
installing the crankshaft
rear
bearing seal

around
the crankshaft, apply a thin coat of light cup grease to both halves of the seal except for the
ends which are already treated with sealing com­ pound. When installing the
rear
main bearing cap

in
the crankcase, place a small amount of plastic- type gasket cement on both sides and face of the
cap to prevent oil leakage. Insert the rubber
packings shown in
Fig. D-3
7
into the
holes
between
the bearing cap and the case. Do not trim
these

packings. The packings are of a predetermined
length that
will
cause them to protrude approxi­ mately 34* [6 mm.] from the case. When the oil

pan
is installed, it
will
force them tightly into the

holes
and effectively seal any opening
between

the bearing cap and the crankcase.

D-86.
Install
Front
End Plate
Assemble the gasket to the front end plate making

certain
that it is positioned properly down to the

bottom
of the crankcase.
Install
the front end plate
on the cylinder block and tighten in place.

D-87.
Install
Flywheel

Be
sure the crankshaft flange and flywheel mating
surfaces are clean to permit proper flywheel align­ ment. With the crankshaft in the cylinder block,
FIG.
D-36—
REAMING FLYWHEEL

FIG.
D-37—REAR
BEARING
CAP
PACKING

64

'Jeep*
UNIVERSAL
SERIES
SERVICE
MANUAL

D D-l 13. HURRICANE
F4
ENGINE SPECIFICATIONS

MODEL:
ENGLISH
ENGINE:

Type

Number of Cylinders

Bore
Stroke
Piston Displacement...........
Bore
Spacing (center to center): 1 and 2, 3 and 4
2 and 3

Firing
Order Compression Ratio Compression Pressure... .
Number of Mounting Points:

Front
Rear

Horsepower (SAE)
Horsepower (Max Brake) Maximum Torque @
2000
rpm.
PISTONS:

Material
Description

Length
,.
Diameter (near
bottom
of
skirt).

Weight.
Clearance
Limits:
Piston-To-Cylindcr
Bore

Ring
Groove Depth:
No. 1 and 2 Ring No. 3 Ring

Ring
Groove Width:
No. 1 Ring No. 2 Ring
No. 3 Ring
Piston Pin Hole Bore
Cylinder
Bore — Standard.....
—
max. out of round
F-Head

4

W

134.2 cu. in.

3.437"

4.938"

1-3-4-2
6.7:1
120 to 130 psi.
2
1
15.63

@
4000
rpm. 114 lb-ft. 75

-
max. taper..

-
max. rebore.

PISTON RINGS:
Function:

No. 1 and 2 No. 3. .

Material:

No. 1. .
No. 2 and 3

Width;
No. 1 and 2
No. 3. . . .

Gap
(Std. to .009 Cyl. Bore).
Thickness:
No. 1 and No. 2 Rings....
No. 3 Ring
Side Clearance in Groove:
No. 1 Ring No. 2 Ring
No. 3 Ring

PISTON
PINS:
Material

Length
Diameter

Type

Clearance
in Piston
(selective
fit).
Aluminum
Alloy

Gam
Ground, T-slot, Tin Plated

3.1225*
to
3.1245*
13.5 oz.
Selective Feeler Fit
.1593" to .1655"
.1693" to .1755"
.0955" to .0965" .095" to .096"
1875" to .1885" .760" to .770"

3.125"
to
3.127"
.005" .005" .040"
Compression
Oil

Cast
Iron,
Chrome-plated Face
Cast
Iron

.007" to .017"
.134" to .144" .115" to .125"
.002" to .004"
.0015" to .0035" .001" to .0025"

SAE
1016 Steel
2.781"
.8119"

Locked
in Rod

.0001"
to .0003"
METRIC

7,937
cm.

11,112
cm. 2199 cm*

8,729
cm.

12,542
cm.
8,4 a 9,2 kg-cm2
15,77 kg-m.
9,525
cm.

7,9311
a
7,9362
cm.

382,7
gr.

4,046
a
4,203
mm.
4,300
a
4,457
mm.

2,4257
a
2,4511
mm. 2,413 a
2,438
mm.

4,7625
a
4,7879
mm.
19,304
a
19,558
mm.
7,9375
a
7,9425
cm.

0,1270
mm.

0,1270
mm.
1,0160
mm.
2,38 mm.
4,76 mm.
0,178 a
0,432
mm.

3,403
a
3,657
mm. 2,821 a 3,175 mm.
0,051 a 0,102 mm.
0,038
a
0,088
mm.

0,025
a
0,063
mm.

70,637
mm.

20,6223
mm.

0,0025
a
0,0076
mm. 71

D

HURRICANE
F4
ENGINE
D-l
13
HURRICHNE
F4
ENGINE
SPECIFICATIONS
(Continued)

MODEL:
CONNECTING
RODS:
Material.

Weight
Length
(center to
center)......

Bearing:
Type.
Material

Length
Over
All
Clearance
Limits.
..........
Undersize
Bearings
Available

End
Play

Installation

Bore:
Upper

Lower

CRANKSHAFT:
Material....................

End
Thrust

End
Play
Main
Bearings:
Type.
Material

Clearance

Undersize
Bearings
Available

Journal
Diameter

Bearing
Length:
Front.
No.
2. . .

No.
3

Out
of
round
and out of taper
limits

Direction
of
Cylinder
Offset..........

Amount
of
Cylinder
Offset
Crankpin
Journal
Diameter

Flywheel
Run Out
(max.)
ENGLISH

CAMSHAFT:
Bearings:
Material..........
Number

Clearance.

Journal
Diameter:

Front Front
Intermediate.
Rear
Intermediate..
Rear

Bearing
Diameter:

Front Front
Intermediate.
Rear
Intermediate..

Rear

End
Play
Drive:

Type.............
Crankshaft
Gear.
. .

Camshaft
Gear

VALVE
SYSTEM:
Valve
Rotators
Tappets:
Clearance
—
Cold:

Intake

Exhaust

Clearance
for
Timing
(intake).
SAE
1141
Forged
Steel
32 oz.
9.187"

Removable

Steel-backed
Babbitt
1.089" to 1.099"
.001"
to .0019"
.001" .002"
.010"
.012" .020" .030"
.004"
to .010"
From
Above

.8115"
to .8125"

2.0432"
to 2.0440"

SAE
1040
Forged
Steel
Front
Bearing
.004*
to .006*

Removable

Steel-backed
Babbitt
.0003"
to .0029*
.001"
.002" .010"
.012" .020"
.030"

2.333"
to 2.334"
1.64"
1.72"
1.66"
.001"

Right
.125"

1.9375" to
1,9383
.005"

Steel-backed
Babbitt
(Front
only) 4

.001"
to .0025"
2.1860" to 2.1855"

2.1225"
to 2.1215"
2.0600" to 2.0590" 1.6230" to 1.6225"
2.1870" to 2.1890"
2.125"
to 2.126"

2.0625"
to 2.0635"
1.625" to 1.626"
.004*
to .007"

Helical
Gear
Cast
Iron

Pressed
Fiber-Steel
Hub

On
Exhaust
Valve

.018*
.016* .026"
METRIC

907
gr.
23,33 cm.
2,766 a 2,791 cm.
0,025 a 0,0483 mm.
0,025 mm. 0,051 mm.

0,254
mm.
0,305 mm. 0,508 mm.
0,762 mm.
0,102 a
0,254
mm.
20,612 a 20,637 mm. 5,1897 a 5,1917 cm.
0,102 a 0,152 mm,
0,0076 a 0,0736 mm. 0,025 mm.
0,051 mm.
0,254
mm.
0,305 mm.
0,508 mm.
0,762 mm.

5,9261
a 5,9286 cm.
4,16 cm.
4,36 cm.
4,21 cm.
0,025 mm.
3,175 mm.
4,9213 a 4,9233 cm. 0,127 mm.
0,025 a
0,063
mm.
5,5524 a
5,5511
cm.

5,3911
a 5,3886 cm.
5,2324 a 5,2298 cm.
4,1224 a
4,1211
cm.
5,5549 a 5,5600 cm.
5,3975 a 5,4000 cm. 5,2387 a 5,2412 cm.
4,1275 a 4,1300 cm. 0,101 a 0,178 mm.
0,461 mm. 0,406 mm.

0,660
mm. 72

'Jeep'
UNIVERSAL SERIES SERVICE
MANUAL

D
D-l 13. HURRICANE
F4
ENGINE SPECIFICATIONS
(Continued)

MODEL:

VALVE
SYSTEM:
(Continued) Timing: Intake:
Opens Closes
Duration
Exhaust: Opens
Closes Duration
Valve Opening Overlap
Valves: Intake: Material
Length Over All. Head Diameter.
.........

Angle
of Seat.
Stem
Diameter
Stem-to-Guide
Clearance..

Lift

Exhaust: Material
Length Over All Head Diameter

Angle
of
Seat Seat
Insert Material

Stem
Diameter

Stem-to-Guide
Clearance..
Lift

Springs: Intake:
Free
Length Standard: Pressure % Length: Valve Closed........
Valve Open
Service Minimum: Pressure @ Length: Valve Closed Valve Open
Exhaust:
Free
Length Pressure @ Length: Standard: Valve Closed
Valve Open
Service Minimum: Valve Closed. Valve Open

LUBRICATION SYSTEM:
Type of Lubrication:

Main
Bearings Connecting Rods
Piston Pins Camshaft Bearings
Tappets
Timing Gears.'.
Cylinder
Walls

Oil
Pump: Type Drive
Minimum
Safe
Oil Pressure:
At
Idle
At
2000
rpm. (35 mph.)..
Relief Valve Opens Normal Oil Pressure

Oil
Pressure
Sending
Unit

Oil
Intake
Oil
Filter
System
ENGLISH
9°
BTC

50°
ABC
239°

47°
BBC 12* ATC
239°
21°
SAE
5150
4.781"
2*

46°

.3733"
to
.3738"
.0007"
to
.0022'
.260"
Uniloy 21-12
5.909"
1.47"

46°

Eatonite EMS 58 .371" to .372"

.0025"
to
.0045'

.351"
1.97"
73 lb. @ 1.66"
153 lb. @ 1.40* 66 lb.
140 lb. 1.66*

)
1.40" 53 lb. (
120 lb.
2.109"

\
1.750*

47 lb. @2W
110 lb. @ l%*
Pressure
Pressure Splash
Pressure
Splash

Nozzle
Nozzle

Internal
Rotor
Camshaft
Gear

6 psi.
20 psi.
40 psi.
35 psi. @
2000
rpm.
Electric

Floating

Partial
Flow
METRIC

12,14 cm. 5,08 cm.
9,481 a
9,494
mm.

0,0178
a
0,0559
mm.
6,604
mm.

15,008
cm.
3,733
cm.

9,423
a
9,449
mm.

0,0635
a
0,1143
mm. 8,915 mm.

5,003
cm.
33,1 kg.
(i(<
4,216 cm.
69,4 kg. (a.
3,556
cm.
29,9 kg. (d 4,216 cm.
63,5 kg. ((i
3,556
cm.

6,350
cm.
24 kg. (a
5,356
cm.
54,3 kg. (a
4,445
cm.
21,3 kg. (n 5,
356cm.

49,9 kg. («
4,445
cm.
0,4 kg-cm2 1,4 kg-cm2
2,8 kg-cm2
2,4 kg-cm2 @
2000
rpm. 73

'Jeep*
UNIVERSAL
SERIES SERVICE
MANUAL

Dl

12713

FIG.
Dl-11—MEASURING
TELESCOPE GAUGE
1—
Telescope
Gauge
2—
Micrometer

may
be measured with an inside micrometer or
by setting the cylinder
gauge
dial
at zero and meas­
uring
across the
gauge
contact points with an out­side micrometer while the
gauge
is at same zero
setting. Refer to
Figs.
Dl-10 and Dl-11.

b.
If a cylinder bore is moderately rough or slightly

scored,
but is not out-of-round or tapered, it is

usually
possible to remedy the situation by honing
the bore to fit a standard service piston, since
standard
service pistons are high-limit production
pistons. If cylinder bore is very rough or deeply
scored,
it may be necessary to rebore the cylinder
to fit an oversize piston in order to ensure satisfac­
tory
results.

c.
If cylinder bore is tapered .005" [0,127 mm.]

or
more or is out-of-round .003" [0,076 mm.] or

more,
it is advisable to rebore for the smallest possible oversize piston and rings.

d.
Carefully
inspect the cylinder block for small

cracks
or fractures, and for porosity.
Rust
in any
cylinder
bore may indicate a leak.

e.
Inspect all machined surfaces for scoring and

burrs.
With
a straight
edge
and feeler
gauge,
check
each
machined surface for distortion.

D1-37.
Cylinder Block Repair
If
one or more cylinder bores are rough, scored, or

worn
beyond prescribed limits, it
will
be necessary
to correct bores and fit new pistons.

If
relatively few bores require correction, it
will

not be necessary to rebore all cylinders to the same
oversize in order to maintain
engine
balance, since
all
oversize pistons are held to the same weights as

standard-size
pistons. If conditions justify replace­
ment of all pistons, however, all new pistons should
be the same nominal size.

Standard-size
service pistons are high-limit, or

maximum
diameter; therefore, they can usually be installed after a slight amount of honing has
been
done
to correct slight scoring or excessive

clearances.
This
applies
primarily
to
engines
which
have relatively low mileage. Service pistons are also furnished in .010"
[0,254
mm.] oversize. All

service
pistons are diamond bored, and selectively
fitted with piston pins; pistons are not furnished
without pins.

Caution:
Do not attempt to cut down oversize pis­

tons
to fit cylinder bores as this
will
destroy the

surface
treatment and affect the weight. The small­
est possible oversize service pistons should be used

and
the cylinder bores should be honed to size

for
proper clearance.

Before
honing or reboring cylinders, measure all new pistons with a micrometer, on an axis perpen­

dicular
to the piston pin. Select the smallest piston

for
the first fitting. The slight variation usually
found between pistons in a set may provide for
correction
in case the first piston tried is too

small.

If
wear at top of cylinder
does
not exceed .005" [0,127 mm.]
excess
diameter, or exceed .003"
[0,076 mm.] out-of-round, honing is recommended.

If
wear or out-of-round
exceeds
these
limits, the
bore should be reground with a boring bar of the

fly
cutter type, then finish-honed.

When
reboring cylinders, all crankshaft bearing caps must be in place and tightened to proper
torque to avoid distortion of bores in
final
assem­
bly.
Always be sure the crankshaft is out of the

way
of the boring cutter when boring each cylinder.
When
boring, leave the diameter .001" [0,025 mm.]

undersize,
then finish hone to obtain the required

clearance.

When
honing cylinders, use clean sharp
stones
of
proper
grade for the amount of metal to be re­
moved. Refer to instructions supplied by the hone
manufacturer.
Dull
or dirty
stones
cut unevenly

and
generate excessive heat. When using coarse

or
medium grade
stones,
leave sufficient metal so
that all
stone
marks can be removed with the fine
stones
used to finish-hone to proper clearance.

When
finish-honing, pass the hone through the entire length of cylinder at a rate of approximately 60 cycles per minute.
This
should produce the

desired
45-degree
cross hatch pattern on cylinder

walls.
A proper pattern
will
ensure maximum
ring
life and minimum oil consumption.

After
final
honing and before the piston is checked

for
fit, each cylinder bore must be washed thor­ oughly to remove all traces of abrasive, then dried completely. The dry bore should be brushed clean

with
a power-driven fibre
brush.
If all traces of

abrasive
are not removed,
rapid
wear of new pistons

and
rings
will
result.

Note:
Wipe cylinder bores with a clean white

cloth,
moistened with SAE 10 oil. Cleaning should
continue until this
test
shows no sign of
dirt.

It
is of the greatest importance that refinished

cylinder
bores be true, with .0005" [0,013 mm.]
or
less out-of-round or taper.
Each
bore must have

a
smooth surface, without
stone
or cutter
marks.
After
final
honing and cleaning, each piston must be fitted individually to the bore in which it
will

be installed. Once fitted, each piston should be
marked
with its cylinder number to assure correct

installation.
85