Table of Contents
Advertisement
6A2-18
1977 PONTIAC SERVICE MANUAL
Remove
1. Remove oil pan.
2. Remove cap on main bearing requiring replacement
and remove bearing.
3. Using a thin object such as a small screwdriver, rotate
the upper half of the bearing in the direction of the tab and
slide bearing out. It may be necessary to loosen other main
bearings to gain clearance.
Main Bearing Clearance
1. Place a .002" brass shim between the crankshaft
journal and the lower bearing in each bearing cap next to the
one being checked. This causes the crankshaft to be forced
against the upper bearing and insures an accurate
measurement of the total clearance.
2. Remove the bearing cap of the bearing to be checked.
Wipe the bearing and the journal free of oil.
3. Place a piece of plastic gage, the length of the bearing
(parallel to the crankshaft), on the journal or bearing surface
(Fig. 6A2-40).
NOTE: Plastic gage should be positioned exactly in the
middle of the upper or lower bearing shell. Bearings are
eccentric and a false reading could occur.
Install the cap and tighten cap bolts to proper torque.
(Do not turn crankshaft with plastic gage in place).
Fig.
6 A 2 - 4 0
Plastic Gage On Journal
4. Remove bearing cap and using plastic gage scale on
envelope measure width of compressed plastic gage before
removing it from the bearing or journal (Fig. 6A2-41). If the
clearance is excessive, replace the bearing with the next
undersize bearing and recheck clearance. Bearings are
available in standard size, ,001
"
and .002" undersize.
5. Install a new rear main bearing oil seal in the cylinder
block and main bearing cap if the rear main bearing was
checked and/or replaced.
Fig.
6A2-4
1 Measuring Plastic Gage
Replace
1. Oil new upper bearing shell and insert plain
(unnotched) end of shell between crankshaft and indented or
notched side. Rotate the bearing into place.
2. Install new bearing shell in bearing cap.
3. Check bearing clearance using plastic gage method.
4. Install oil pan using new gaskets and seals.
CONNECTING ROD A N D PISTON
ASSEMBLY
Remove
1. Remove cylinder head as described in cylinder head
or gasket.
2. Remove oil pan as described in oil pan remove.
3. Check connecting rod and piston for cylinder number
identification and if necessary, mark them.
4. Remove bearing cap and install connecting rod bolt
guide set, J6305- 1 1.
5. Carefully remove connecting rod and piston assembly
by pushing out with knurled handle of long guide.
PISTON RINGS
Install
Incorrect ring gap indicates that wrong size rings are
being used. If rings are selected according to the size of the
bore, they should have the proper gap. It should not be
necessary to alter ring gap by filing.
4. Install rings on piston, using suitable ring installing
tool to prevent breakage or fracture of rings, or damage to
pistons.
5. Measure side clearance of rings in ring groove (Fig.
6A2-43) as each ring is installed.
If side clearance is excessive, piston should be replaced.
PISTON A N D ROD ASSEMBLY
Disassemble
Advertisement
Table of Contents
