Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual, Page: 78 / 413

3rd
re-issue
Page40
SPRING
BALANCE
FEELER
STRIP
Fig. 46.
Checking piston c/eoronce with feeler
and spring balance
to bore the maximum diameter of the piston plus
its prescribed clearance In the cylinder bore less a
small amount for honing.
The honing operation allows the bore size to be
taken to the size that will allow the piston to be
correctly fitted using a feeler to check the clearance
as previously described and illustrated In Fig. 46.
It Is advisable to regrind and reset the cutter after
completing each cylinder bore.
Bores must be parallel and round to within ·0004'
(·01 mm.). The use of a cylinder gauge such as a
Mercer is recommended for taking measurements.
Top, middle and bottom of each bore should be
checked both In line with and at right angles to the
gudgeon pin axis.
SERVICE REPLACEMENT
CYLINDER
BLOCK
It Is normal practice to supply cylinder blocks
separately, but a set of suitably graded pistons can
be supplied to suit any given block. Cylinder blocks
WSM.124
Section B (Engine}
complete with pistons are not serviced under one
part number.
It Is essential to ensure that each new piston is
fitted into a bore of appropriate grade.
CYLINDER LINERS
To flt
These Instructions apply to engines which are not
fitted with liners during initial assembly. Some
engines, however, are fitted with liners during
production and these should be dealt with as
described under "CYLINDER LINERS-To renew".
If the fitting of liners is to prove really successful
a high degree of skill on the part of the operator
is required, coupled with first-class precision
equipment.
If, however, after considerable mileage, it should be
decided to Install liners, It is absolutely essential
that the procedure laid down in the ensuing
paragraphs Is rigidly adhered to, as otherwise there
is every possibility of the operation proving un­
satisfactory.
1494 c.c. Engine
The outside diameter of the cylinder liner Is
3·25r-3·258' (82-n-82-75 mm.). Cylinders should
be bored to 3·254'-3·255' (82·65-82·67 mm.).
1592 c.c. Engine
The outside diameter of the cylinder liner is 3·357'-
3·358' (85·267-85·293 mm.). Cylinders should be
bored to 3.354•_3.355• (85·191-85·217 mm.).
Remove engine from chassis and dismantle.
Measure external diameter of liners.
Measure diameter of bores below piston ring travel.
Bore out the cylinders to suit liners, allowing for
the prescribed Interference fit of
-oor-·004"
(0·051-0·102 mm.). It is Imperative that the correct
figures are strictly adhered to. Every possible
precaution must be taken to ensure concentricity
and correct size for the full length of the bore.
Finish boring must not be attempted until all liners
have been fitted.
Press in liners. To facilitate fitting, a "lead-in" is
provided at the lower end of the liner.
When inserting the liners, the load should be
released several times during the first inch or so;