Alfa Romeo alfa 33 Workshop Manual page 71

Dimensions relevant to each class are
shown in: Service Data and Speci-
"Cylinder block" chart.
fications
(1) Reset the reamer by means of a
micrometer.
(2) Measure the diameter at the
m i n e t a p e r a n d o u t - o f - r o u n d o f
cylinders walls.
ENGINE MAIN MECHANICAL UNIT
Cylinder wall max. taper:
A - B = 0.02 mm (0.00079 in)
Cylinder wall max. out-of-round:
X - Y = 0.02 mm (0.00079 in)
(3) Compare actual values D with
nominal ones C of each size class and
then determine the cylinders walls
max. wear.
Cylinder wall max. wear:
C - D = 0.04 mm (0.00157 in)
4. If the dimensions thus estab-
lished are not within tolerance,
cylinders walls must be rebored
keeping in mind that three different
oversize pistons are available as spare
parts; this means that the diameter of
walls will have to be in accordance
with the tolerances shown in: Service
Data and Specifications "Cylinder
block" chart.
(1) Mount main bearing caps on the
cylinder block and tighten screws as
specified in: "Engine assembly -
Engine unit".
Then proceed to bore cylinder walls
so as to stay within the tolerances
shown in: Service Data and Speci-
fications - "Cylinder block" chart.
Lapping must be performed so that
tool marks cross each other at an
angle of 9CP + 1203
(2) If wear does not exceed the
specified limit but pistons and spring
rings need replacing because of some
flaws or damage, cylinders walls
will need at least to be lapped; in this
case measure the diameter of the
wails in order to identify the new
size class to which they belong
and that will have to be kept in mind
during piston fit operations, regar-
dless of the letter stamped on the
cylinder block. Should lapping cause
a size class change, cylinder wall will
no longer be identifiable through the
letter stamped on the cylinder block
which, therefore, must be erased in
order to avoid mistakes during future
operations_
0 1 - 2 3
PISTON - CYLINDER
WALL FIT
1. When original parts are involved,
they will be selected by matching
each cylinder wall identification
letter that is stamped on cylinder
block upper surface to the piston
that has the same letter stamped on
its head or a coloured dot painted on
the inside of its crown, according to
the following schedule:
Wall 8
identifying
Engine identifying
letter and
letter
A - b l u e
B - p i n k
1350
C - green
D - yellow
1500
E
If the letter stamped on the cylinder
block has been previously erased,
matching will take place according to
the identification letter stamped on
the piston that needs replacing; in
this instance, it is advisable to make a
d o u b l e c h e c k a n d m e a s u r e t h e
cylinder wall diameter.
2. When oversize walls are used,
they will be matched to the relevant
completely assembled
namely with compression rings and
oil scraper ring, which are available as
spare parts according to the follow-
ing oversize scale: G.2 - 0.4 - 0.6 mm
(0.0078 - 0.0157 - 0.0236
Piston
colour
pistons,
in).
May 1983