Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual, Page: 73 / 413

WSM.124
Section B (Engine)
Tighten nuts to the correct torque given in the
Data Section under "Connecting Rod".
IMPORTANT
These nuts are #" x 24 T.P.I. UNF. Care is needed
to ensure that f" x 24 T.P.I. UNF nuts, used on other
Rootes Group engines, are not fitted when replacement
nuts are required.
As
the larger i" nuts have the same
number of threads per inch they can easily be screwed
onto the
tr
x 24 T.P.I. big end bolt thread and will
strip the threads when tightened to about 12 lbs. ft.
torque (
/
·5 kgm).
The self-locking nuts must not be used again If they
can be screw�d on with the fingers.
To remove gudgeon pin
Remove circllps retaining gudgeon pin in piston
with circllp pliers. Scrape away any carbon which
may have accumulated in the outer ends of the
piston bosses to facilitate removal of the gudgeon
pin.
Warm the assemblies, preferably in oil, and push
out the gudgeon pins. Tight fitting gudgeon pins
should not be driven out of cold pistons.
To assemble
The original piston, gudgeon pin and small end bush
may be used again, if the gudgeon pin Is without
shake, both in the piston bosses and In the small
end bush.
New clrcllps of the correct size should be fitted.
The smaller circlips used on the 1390cc and 1494cc
engines must NEVER be fitted to pistons used in
1592cc engines.
Gudgeon Pin Fits
At room temperature of 70
°
F. (21
°
C.) the gudgeon
pin should be a finger push fit In the piston and only
just free In the connecting rod little end bush. It
should be possible for the connecting rod to fall by
its own weight when the piston and connecting rod
assembly Is held horizontal.
Gudgeon pins are classified Into three grades.
Grade diameters are given In the General Data
section under Gudgeon Pin.
,003• (·076 mm.) oversize gudgeon pins are available
for service use.
Delapena Precision Honing Machine
This honing machine, illustrated in Fig. 39, is
3rd
re-issue
Page 35
recommended for honing new little end bushes to
standard size or to + 003" ( ·076 mm.) oversize. It
can also be used to hone out the piston bosses to
take the oversize gudgeon pin.
The following equipment is used with this machine:
Mandrel SL.900
Truing sleeve ST.900
Roughing stone EF3J
Finishing stone EF6J
Polishing stone EF8J
Delapena connecting rod clamps
Delapena honing fluid. (Standard)
Complete Instructions for the operation of this
machine are contained in a booklet (Publication
No. C.3 /55) of which two copies are sent with each
machine by the suppliers, Delapena & Sons Ltd.,
Zona Works, Cheltenham, England.
In using the Delapena honing machine It Is stressed
that the work must be kept as c�ol as possible at all
times. Only by so doing can an accurate and round
bore can be achieved. Heating of the little end boss
which can occur due to pressure of the boss, can
cause the boss to go "out of round" temporarily.
This will not occur if a receptacle containing honing
fluid is kept by the machine and the work dipped in
it frequently.
Honing Little End Bush (See Fig. 40)
Flt the appropriate Mandrel In the machine with
roughing stone and true up stone with truing
sleeve; hone out the little end bush until It is ·0005"
(·012 mm.) below the finished diameter. To
determine this size, useful check gauges can be
made by reducing a I " (25 mm.) length of standard
and oversize gudgeon pins to ·0005" (·012 mm.)
below their finished diameter. Proceed with the
honing, using a finishing stone in the mandrel.
The stone must be trued with the truing sleeve
before honing is commenced. In performing this
last stage of honing great care Is necessary as