Honda Acura NSX 1991, Service Manual

Page: 137 / 1420

Main Bearings
Rod Bearings
Clearance
1 .
2.
3.
4.
5.
6.
To check main bearing clearance, remove the main
caps and bearing halves.
Clean each main journal and bearing half with a
clean shop rag.
Place one strip of plastigage across each main
journal.
NOTE: If the engine is still in the car when you bolt
the main cap down to check clearance, the weight
of the crank and flywheel will flatten the plastigage
further than just the torque on the cap bolts, and
give you an incorrect reading. For an accurate
reading, support the crank with a jack under the
counterweights and check only one bearing at a
time.
Reinstall the bearings, caps and cap bridge, then
torque the 9 mm bridge bolts to 40 14.0 kg-m,
29 Torque the 11 mm cap bolts to 66
(6.6 kg-m, 48 lb-ft).
Torque the side bolts to 50
(5.0 kg-m, 36
Remove the bridge, caps and bearings, and
measure the widest part of the plastigage.
Main Bearing Clearance:
Standard
0.024-0.048 mm
(0.0009-0.0019 in)
Service Limit:
0.05 mm (0.002 in)
If the plastigage measures too wide or too narrow,
(remove the engine if it’s still in the car), remove
the crank, remove the upper half of the bearing,
then install a new, complete bearing with the same
color code (select the color as shown
next
page), and recheck the clearance.
CAUTION:
D
O
not file, shim, or scrape the bear-
ings or the caps to adjust clearance.
If the plastigage shows the clearance is still incor-
rect, try the next larger or smaller bearing
color
listed above or below that one), and check again.
NOTE: If the proper clearance cannot be obtained
by using the appropriate larger or smaller bearings,
replace the crank and start over.
Clearance
1 .
2.
3.
4.
5.
Remove the connecting rod cap and bearing half.
Clean the crankshaft rod journal and bearing half
with a clean shop reg.
Place plastigage across the rod journal.
Reinstall the bearing half and cap, and torque the
nuts to 20
(2.0 kg-m, 14 lb-ft), then turn
(page 7-l
NOTE: Do not rorate the crank during inspection.
Remove the rod cap and bearing half and measure
the widest part of the plastigage.
Connecting Rod Bearing Clearance:
Standard (New): 0.04-0.06 mm
10.0016-0.0024 in)
Service Limit: 0.06 mm (0.0024 in)
STRIP
6.
7.
If the plastigage measures too wide or too narrow,
remove the upper half of the bearing, install a new,
complete bearing with the same color code (select
color as shown on next page), and recheck the
clearance.
CAUTION: Do not file, shim, or scrape the bearing
or the caps to adjust clearance.
If the plastigage shows the clearance is still incor-
rect, try the next larger or smaller bearing (the color
listed above or below that one), and check
clearance again.
NOTE: If the proper clearance cannot be obtained
by using the appropriate larger or smaller bearings,
replace the crank and start over.
7-7