GMC C Series 1993, Руководство по ремонту

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6A2-28 V8 ENGINES, GASOLINE
B, Use a dial indicator as shown. |
C. If the main journals are misaligned, the crank­
shaft is bent and must be replaced, along with
» ; the main bearing.
CRANKSHAFT GRINDING
A- “tufftriding” hardening process is applied to the
7.pL engine crankshaft. This crankshaft should not be
reground unless it can be tufftrided after grinding.
9
Important
•A fte r heat treating, the crankshaft should be
checked for warpage, touched up, and polished pri­
or to assembly.
ASSEMBLY OF THE ENGINE
PRIOR TOASSEM BLY
5. Main; bearing cap (132 and 133).
The importance of cleanliness during the assembly . !
procedure'cannot be overstressed. Dirt will cause pre- NOTICE: See “ N o tic e " on page
6 A 2 *1 .
mature wear of the rebuilt engine.
Lubricate all moving parts lightly with engine oil or ;;:-r ;; ^
engine assembly lubricant (unless specified otherwise) 6. Main bearing cap bolts (134).
during assembly. This will provide initial lubrication
when the engine is started. ■ '
CRANKSHAFT AND MAIN
BEARING INSTALLATION
Main bearings are of the precision insert type and do
not use shims for adjustment. If clearances are exces­
sive, a new bearing plus both upper and lower inserts
will be required. Service bearings are available in stan­
dard size and 0.001 inch, 0.002 inch, 0.010 inch, and
0.020 inch undersize. |
Selective fitting of both rod and main bearing inserts
is necessary in production to obtain close tolerances.
For this reason you may find one half of a standard
insert with one half of a 0.001 inch undersize insert that
will decrease the clearance 0.0005 inch from using a
full standard bearing. ;
MAIN BEARING SELECTION
The simplest most accurate way to rneasure main
bearing clearance is with the use of gaging plastic. This
wax-like material compresses evenly between the bear­
ing and journal surfaces Without damaging them. Pro­
ceed as follows:
Install or Connect (Figures 59, 60, and 61)
1. Upper main bearing inserts,(136) to the block.
• Apply engine oil to the inserts.
• If any undersized bearings are used, make
/ absolutely certain they are fitted to the proper.
, journal. 1 '
2. Crankshaft (130). Do not damage the thrust areas.
3. Lower bearing inserts (135) to the bearing caps
(132 and 133). : \
; 4. Gaging plastic. !
5> /A. Begin with the rear main bearing. i ;
B. Wipe the oil from the crankshaft journal and the
lower main bearing insert.
C. Place a piece of gaging plastic the full width of
the lower bearing insert (paraller to, the crank­
shaft) on the journal (figure 60), Do not rotate
J > ; the crankshaft while the gaging plastic is
, • between the bearing and journal.
130. Crankshaft
131. Rear Seal ,
v ;
132. Rear Main Bearing Cap
133. Main Bearing Cap
134. Bolt
135. : Lower Main Bearing Insert ,
136. Upper Main Bearing Insert
F9332
Figure 59—Crankshaft and Components