1997 ACURA NSX Service Repair Manual

Rocker Arm s an d Shaft s
Disassembly/Reassembl y
CAUTION: Afte r installin g th e rocke r shaf t orifice , tr y t o tur n th e rocke r shaf t t o mak e sur e tha t th e orific e ha s bee n
inserte d in th e hol e o f th e rocke r shaf t correctly . I f th e orific e i s i n place , i t shoul d no t turn .
NOTE :
• Identif y part s a s the y ar e remove d t o ensur e reinstallatio n i n origina l locations .
• Inspec t rocke r shaft s an d rocke r arm s (se e page s 6-3 3 an d 6-34 ).
• Rocke r arm s mus t b e installe d i n th e sam e positio n i f reused .
• Adjus t th e rocke r arm s afte r torquin g th e cylinde r hea d bolts .
Prio r t o reinstalling , clea n al l th e part s i n solvent , dr y them , an d appl y lubrican t t o an y contac t surfaces .
EXHAUST ROCKE R AR M ASSEMBLIE S
WASHER S
Replace .
INTAKE ROCKE R
SHAF T
WASHER S EXHAUS T ROCKE R
Replace . SHAF T RUBBE
R BAN D
RUBBE R BAN D
CYLINDE R NUMBE R
CYLINDE R NUMBE R
RUBBER BAN D
RUBBE R BAN D
EXHAUS T ROCKE R AR M ASSEMBLIE S
INTAK
E ROCKE R
SHAF T
EXHAUS
T ROCKE R
SHAF T
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Rocker Arms and Lost Motion Assemblies

Inspection

NOTE: When reassembling the primary rocker arm, care-

fully apply air pressure to the oil passage of the rocker

arm.

PRIMARY ROCKER ARM

MID ROCKER ARM

SECONDARY

ROCKER ARM

PISTONS

1. Inspect the rocker arm pistons. Push them manually.

— If they do not move smoothly, replace the rocker

arm assembly.

PRIMARY

MID

SECONDARY

Check piston movement

NOTE:

• Apply oil to the pistons when reassembling.

• Bundle the rocker arms with rubber bands to

keep them together as sets.
2. Remove the lost motion assembly from the cylinder

head and inspect it. Pushing it gently with the finger

will cause it to sink slightly. Increasing the force on

it will cause it to sink deeper.

— If the lost motion assembly does not move

smoothly, replace it.

LOST MOTION ASSEMBLYProCarManuals.com

Rocker Arm s an d Shaft s
Clearanc e
Measure bot h th e intak e rocke r shaft s an d exhaus t rocke r
shafts.
1. Measur e diameter of shaf t a t firs t rocke r location .
MICROMETE R
Surface shoul d b e smooth .
2 . Zer o gaug e t o shaf t diameter .
MICROMETE R
CYLINDER BOR E
GAUG E
3. Measur e insid e diamete r o f rocke r arm , an d chec k fo r
out-of-roun d condition .
Rocker Arm-to-Shaf t Clearanc e (Intak e an d Exhaust) :
Standar d (New) :
Primar y an d Secondary :
0.025-0.052 m m (0.0010-0.002 0 in )
Mid :
0.024-0.05 3 m m (0.0009-0.002 1 in )
Servic e Limit : 0.0 8 m m (0.00 3 in )
Inspec t rocke r ar m
fac e fo r wear .
Repea t fo r al l rockers .
— If ove r limit , replac e rocke r shaf t an d al l over -
toleranc e rocke r arms .
NOTE : I f an y rocke r ar m need s replacement , replac e
al l thre e rocke r arm s i n tha t se t (primary , mid , an d
secondary) .
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Camshafts

Inspection

NOTE:

• Do not rotate the camshaft during inspection.

• Remove the rocker arms and rocker shafts.

1. Put the camshafts, the camshaft holders and holder

plates on the cylinder head, and then tighten the

bolts to the specified torque.

NOTE: Apply clean engine oil to 8 mm bolt threads.

Specified torque:

8 mm x 1.25 mm bolts:

22 N-m (2.2 kgf-m, 16 Ibf-ft)

6 mm x 1.0 mm bolts:

9.8 N-m (1.0 kgf-m, 7.2 Ibf-ft)

CAMSHAFT HOLDER BOLTS TORQUE

SEQUENCE
2. Seat the camshaft by pushing it toward the left end of

cylinder head.

3. Zero the dial indicator against the left end, then push

the camshaft back and forth, and read the end play.

Camshaft End Play:

Standard (New): 0.05 - 0.15 mm

(0.002 - 0.006 in)

Service Limit: 0.5 mm (0.02 in)

4. Remove the bolts, then remove the camshaft holders

from the cylinder head.

5. Lift the camshaft out of the cylinder head, wipe it

clean, then inspect the lift ramps. Replace the

camshaft if lobes are pitted, scored, or excessively

worn.

6. Clean the camshaft bearing surfaces in the cylin-

der head, then set the camshaft back in place.

7. Insert a plastigage strip across each journal.

8. Install the camshaft holders, and then tighten the

bolts to the specified torque as shown in the left

column on this page.

(cont'd)ProCarManuals.com

Camshafts

Inspection (cont'd)

9. Remove the camshaft holders and measure widest

portion of plastigage on each journal.

Camshaft-to-Holder Oil Clearance:

Standard (New): 0.050 - 0.089 mm

(0.002 - 0.004 in)

Service Limit: 0.15 mm (0.006 in)

PLASTIGAGE STRIP

10. If camshaft-to-holder oil clearance is out of toler-

ance:

— And camshaft has already been replaced, you

must replace the cylinder head.

— If camshaft has not been replaced, first check

total runout with the camshaft supported on V-

blocks.

Camshaft Total Runout:

Standard (New): 0.03 mm (0.0012 in) max.

Service Limit: 0.04 mm (0.0016 in)

Rotate camshaft

while measuring

— If the total runout of the camshaft is within toler-

ance, replace the cylinder head.

— If the total runout is out of tolerance, replace the

camshaft and recheck. If the oil clearance is still

out of tolerance, replace the cylinder head.
11. Check cam lobe height wear.

Cam Lobe Height Standard (New):

M/T

Check this area for wear.ProCarManuals.com

FRONT BAN K
CYLINDER' NUMBE R
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Valves, Valv e Spring s
an d Valv e Seal s
Replacemen t
NOTE: Identif y valve s an d valv e spring s a s the y ar e
remove d s o tha t eac h ite m ca n b e reinstalle d i n it s origi -
nal position .
1. Usin g a n appropriate-size d socke t an d plasti c mallet ,
lightl y ta p th e valv e retaine r t o loose n th e valv e keep -
er s befor e installin g th e valv e sprin g compressor .
PLASTIC MALLE T
SOCKET
2. Instal l th e sprin g compressor . Compres s th e sprin g
an d remov e valv e keeper .
VALVE SPRIN GCOMPRESSO RATTACHMENTEXTENSION
07MA F - PR9010 A VALV
E SPRIN G
COMPRESSO RATTACHMENT07757 - PJ1010 A
VALV E SPRIN G COMPRESSO R
(Commercially available )Snap-on CF71 1 o r equivalen t
(cont'd)
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Valves, Valve Springs and Valve Seals

Replacement (cont'd)

3. Install the valve guide seal remover as shown.

VALVE SEAL
VALVE GUIDE SEAL REMOVER

(Commercially available)

LISLE P/N 57900 or KD3350

SEAL

PULLER

4. Remove the valve guide seal.

VALVE GUIDE SEAL REMOVER

(Commercially available)

LISLE P/N 57900 or KD3350
M/T:

Intake Valve Dimensions

A Standard (New): 35.9 - 36.1 mm

(1.413 - 1.421 in)

B Standard (New): 111.10 - 111.40 mm

(4.374 - 4.386 in)

C Standard (New): 5.475 - 5.485 mm

(0.2156 - 0.2159 in)

C Service Limit: 5.445 mm (0.2144 in)

D Standard (New): 1.05 - 1.35 mm

(0.041 - 0.053 in)

D Service Limit: 0.85 mm (0.033 in)

Exhaust Valve Dimensions

A Standard (New): 29.9 - 30.1 mm

(1.177 - 1.185 in)

B Standard (New): 109.60 - 109.90 mm

(4.315 - 4.327 in)

C Standard (New): 5.45 - 5.46 mm

(0.2146 - 0.2150 in)

C Service Limit: 5.42 mm (0.2134 in)

D Standard (New): 1.65 - 1.95 mm

(0.065 - 0.077 in)

D Service Limit: 1.45 mm (0.057 in)ProCarManuals.com