Opel 1900 1973 Service Manual page 312

2.. Expand a telescope gage to fit the cylinder bore at
right angles to the piston pin 2-l/2" from top. See
Figure 6A-33.
Figure 6A-33 Checking Cylinder Bores
TELESCOPE
/ G A U G E
MICROMETER
Figure 6A-34 Measuring Telescope Gage
3. Measure the piston to be installed. See Figure
to the piston pin 2-l/2" below the top of piston. The
piston must be between .C008" and .0012" 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.
grees F between parts is sufficient to produce a varia-
tion of .0005".
Fitting New Piston Rings
When new piston rings are installed without reboring
T E L E S C O P E G A U G E
A of 10 de-
ENGINE MECHANICAL AND MOUNTS
cylinders, the glazed cylinder walls should be slightly
dulled without increasing the bore diameter by
means of the finest grade honing stones.
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 ,014" - ,022" (top) and
be .015" - ,055".
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 up. See Figure 6A-35.
1. PISTON
2. NO. I 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 6A.35 Arrangement of Piston Rings
2. Install piston rings so gaps are positioned as shown
in Figure 6A-36.