Opel 1900 1973, Service Manual, Page: 312 / 625

ENGINE MECHANICAL AND MOUNTS
21
2.. Expand a telescope gage to fit the cylinder bore at
right angles to the piston pin from top. See
Figure
cylinders, the glazed cylinder walls should be slightly
dulled without increasing the bore diameter by
means of the finest grade honing stones.
T E L E S C O P E G A U G E
Figure Checking Cylinder Bores
TELESCOPE
/ G A U G E
MICROMETER
Figure Measuring Telescope Gage
3. Measure the piston to be installed. See Figure
The piston must be measured at right angles
to the piston pin below the top of piston. The
piston must be between and smaller
than the cylinder bore.
Both block and piston must be at approximately the
same temperature when measurements are made or
expansion errors will occur.
A
of 10 de-
grees F between parts is sufficient to produce a varia-
tion of
Fitting New Piston Rings
When new piston rings are installed without
New piston rings must be checked for clearance in
piston grooves and for gap in cylinder bores; how-
ever, the flexible oil rings are not checked for gap.
The cylinder bores and piston grooves must be clean,
dry, and free of carbon and burrs.
To check the end gap of compression rings, place the
ring in the cylinder in which it will be used and
square it in the bore by tapping with the lower end
of a piston. Measure the gap with feeler gages.
Piston ring end gap should be (top) and
(2nd) and the oil ring end gap should
be
If gap is less than specified, file the ends of rings
carefully with a smooth tile to obtain proper gap.
Install piston rings as follows:
1. Upper ring is chrome plated and can be installed
either way up. Number two (2) ring has to be in-
stalled with the marking “top” up. Oil ring can be
installed either way
See Figure
1. PISTON
2. NO. COMPRESSION RING INSTALLED
WITH EITHER SIDE UP.
3. NO. 2 COMPRESSION RING INSTALLED
WITH “TOP” MARKING TOWARDS THE TOP.
4. UPPER AND LOWER STEEL BAND RING
INSTALLED WITH EITHER SIDE UP.
5. INTERMEDIATED RING INSTALLED WITH
EITHER SIDE UP.
Figure Arrangement of Piston Rings
2. Install piston rings so gaps are positioned as shown
in Figure