Piston Rings - Install; Checking Ring Side Clearance; Checking Ring Gap - Pontiac Grand Prix Service Manual

SIX CYLINDER ENGINE 8-31
able. Fit of bearings should be checked when engine is
being assembled.
6. Inspect cylinder bores for out-of-round or excessive
taper. See CYLINDER BORES - INSPECT.
PISTON RINGS - INSTALL
Two compression rings and one 3-piece oil control
ring, all above piston pin, are used on pistons for both
standard and premium fuel engines. The compression
rings are taper faced and also have either a step or a
chamber on the inside diameter of the bottom side.
The top compression ring is molybdenum filled, which
results in the center section of the ring sealing edge
appearing porous or grainy. The lower compression
ring is lubrite finished (black).
Always install compression rings with the stamped
markings toward the top of the piston.
New rings are serviced for the standard size pistons,
and for .005", .010", .020" and .03OU oversize pistons.
When selecting rings be sure they match size of piston
on which they are to be installed, i.e. standard rings
for standard pistons, .010" oversize rings for .010"
oversize pistons, etc. Ring gap and side clearance
should be checked while installing rings as follows:
1. Check pistons to see ring grooves and oil return
holes have been properly cleaned.
2. Place ring down at bottom of ring traveled part of
cylinder bore in which it will be used. Square ring in
bore by pushing it into position with head of piston.
3. Measure gap between ends of ring with feeler gauge
(Fig. 6-62). Gaps should be as follows:
Fig. 6-62 Checking Ring Gap
Fig. 6-63 Checking Ring Side Clearance
Compression Rings.
......................
.0058-.0258
...............................
Oil Ring. .0058-.0558
Incorrect ring gap indicates that wrong size rings
are
being used. If rings are selected according to the size of
the bore (standard .005", oversize, etc.) they should
have proper gap. It should not be necessary to alter
ring gap by filing.
4. Install rings on piston using J 8021 to prevent
breakage or fracture of rings, or damage to pistons.
5. Measure side clearance of rings in ring groove (Fig.
6-63) as each ring is installed. Clearance with new
pistons and rings should be .0015-.0050.
If side clearance is excessive, piston should be replace.
CONNECTING ROD AND PISTON ASSEMBLY
-
REPLACE
1. Install c o ~ e c t i n g rod bolt guide set J 5239 on
connecting rod bolts (fig. 6-64).
2. Using piston ring compressor J 6647, insert rod and
piston assembly into cylinder so notch in top of piston
is facing front of engine (Fig. 6-65).
3. From beneath engine, pull connecting rod with
bearing into place against crankpin.
4. Remove guide set J 5239 and install bearing cap.
Tighten cap nuts to 33 lb. ft.
5. Install oil pan.
6. Install cylinder head, intake and exhaust manifold
as an assembly.
7. Connect fuel line and vacuum lines to carburetor.