Chevrolet 1980 Light Duty Truck Service Manual page 479

F ig . 6 A 4 - 5 1 - - R e m o v i n g C o n n e c t i n g R o d & P i s t o n A s s e m b l y
CONNECTING ROD AND PISTON ASSEMBLIES
Removal
1. Remove oil pan, oil pump and cylinder head as
previously outlined.
2. For the cylinder being serviced turn crankshaft until
piston is at the bottom of the stroke. Place a cloth on top
of the piston.
3. Use a ridge reamer to remove any ridge and/or
deposits from the upper end of the cylinder bore.
4. Turn crankshaft until piston is at top of stroke and
remove cloth and cuttings.
5. Remove connecting rod cap and install Tool J-5239
(3/8") on studs. Push connecting rod and piston assembly
out of top of cylinder block (fig. 6A4-51). It will be
necessary to turn the crankshaft slightly to disconnect some
of the connecting rod and piston assemblies and push them
out of the cylinder.
Disassembly
1. Remove connecting rod bearings from connecting
rods and caps. If bearings are being reused, place them in
a rack so they may be reinstalled in their original rod and
cap.
2. Remove piston rings by expanding and sliding them
off the pistons.
3. Place connecting rod and piston assembly on Tool
J-24086-20. Using an arbor press and piston pin remover,
J-24086-8, press the piston pin out of connecting rod and
piston (fig. 6A4-52).
Cleaning and Inspection
Connecting Rods
Wash connecting rods in cleaning solvent and dry with
compressed air. Check for twisted or bent rods and inspect
for nicks or cracks. Replace connecting rods that are
damaged.
FIXTURE
SUPPORT
ASSEMBLY
J -2 4 0 8 6 -2 0
F i g . 6 A 4 - 5 2 ~ R e m o v i n g P i s t o n Pin
Pistons
Clean varnish from piston skirts and pins with a
cleaning solvent. DO NOT WIRE BRUSH ANY PART
OF THE PISTON. Clean the ring grooves with a groove
cleaner and make sure oil ring holes and slots are clean.
Inspect the piston for cracked ring lands, skirts or pin
bosses, wavy or worn ring lands, scuffed or damaged skirts,
eroded areas at top of the piston. Replace pistons that are
damaged or show signs of excessive wear.
Inspect the grooves for nicks or burrs that might cause
the rings to hang up.
Measure piston skirt (across center line of piston pin)
and check clearance.
Piston Pins
The piston pin clearance is designed to maintain
adequate clearance under all engine operating conditions.
Because of this, the piston and piston pin are a matched set
and not serviced separately.
Inspect piston pin bores and piston pins for wear.
Piston pin bores and piston pins must be free of varnish or
scuffing when being measured. The piston pin should be
measured with a micrometer and the piston pin bore should
be measured with a dial bore gage or an inside micrometer.
If clearance is in excess of the .001" wear limit, the piston
and piston pin assembly should be replaced.
Assembly
1. Lubricate piston pin holes in piston and connecting
rod to facilitate installation of pin.
2. Place connecting rod in piston and hold in place
with piston pin guide and piston pin. Place assembly on
SMALL BLOCK 6 A 4-27
PRESS
-PISTON PIN
REMOVER
J - 2 4 0 8 6 -8
LIG H T T R U C K SER V IC E M ANUAL