1991 ACURA NSX Service Repair Manual

Rocker Arm s an d Shaft s
Remova l
1. Scre w a 5 m m bol t int o eac h rocke r shaf t oi l contro l
orifice , the n pul l ou t th e rocke r shaf t oi l contro l ori -
fices .
ROCKE R SHAF T
OI L CONTRO L
ORIFIC E
Clean . 5
m m BOL T
O-RIN G
Replace .
O-RING
Replace .
2. Remov e th e VTE C solenoi d valve , the n remov e th e
sealin g bolts .
WASHE R
Replace .
SEALIN G BOL T
WASHE R
Replace .
FILTER/O-RIN G
Replace .
SEA IN G VTE C SOLENOI D VALV E
BOL T
3. Bundl e th e rocke r arm s wit h rubbe r band s t o kee p
the m togethe r a s sets .
4 . Scre w a 1 2 x 1.2 5 m m bol t int o eac h rocke r shaft .
Remov e th e rocke r arm s whil e slowl y pullin g th e
rocke r shaft s ou t o f th e cylinde r head s towar d th e
transmissio n end .
ROCKE R AR M
ASSEMBL Y RUBBE
R BAN D
12 m m BOL T
1 2 m m BOL T
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Locations
CAUTION: After installing the rocker shaft orifice, try to turn the rocker shaft to make sure that the orifice has been
inserted In the hole of the rocker shaft correctly- If the orifice is in place, it should not turn.

NOTE:
Identify parts as they are removed to ensure reinstallation in priginal locations.

Inspect rocker shafts and rocker arms (see pages 6-32 ('91-'93) or ('94-'96) and 33 ('91-'93) or ('94-'96) .
Rocker arms must be installed in the same position if reused.
Adjust the rocker arms after torquing the cylinder head bolts.
Prior to reinstalling, clean all the parts in solvent, dry them, and apply lubricant to any contact surfaces.

SEALING BOLTS 20 mm
60 N·m (6.0 kg-m, 43 Ib-ftl EXHAUST ROCKER

SHAFT

WASHERS

Replace.
INTAKE ROCKER

SHAFT

Rear Cylinder Head:

SEALING BOLTS 20 mm
6
0
N·m (6.0 kg-m, 43 Ib-ft)

INTAKE ROCKER

SHAFT

WASHERS
Replace. EXHAUST ROCKER
SHAFT INTAKE ROCKER ARM ASSEMBLIES RUBBER BAND
RUBBER BAND
CYLINDER NUMBER
CYLINDER NUMBER
RUBBER BAND
RUBBER BAND
EXHAUST ROCKER ARM ASSEMBLIES EXHAUST ROCKER ARM ASSEMBLIES

Front Cylinder Head:ProCarManuals.com

Rocker Arm s an d Los t Motio n Assemblie s
Inspection
NOTE: Whe n reassemblin g th e primar y rocke r arm , care -
full y appl y ai r pressur e t o th e oi l passag e o f th e rocke r
arm.
PRIMAR Y ROCKE R AR M
MI D ROCKE R AR M
SECONDAR Y
ROCKE R AR M
PISTON S
Inspect th e rocke r ar m pistons . Pus h the m manually .
— If the y d o no t mov e smoothly , replac e th e rocke r
ar m assembly .
PRIMARYMID
SECONDAR Y
Check pisto n movemen t
NOTE:
• Appl y oi l t o th e piston s whe n reassembling .
• Bundl e th e rocke r arm s wit h rubbe r band s t o
kee p the m togethe r a s sets . 2
. Remov e th e los t motio n assembl y fro m th e cylinde r
hea d an d inspec t it . Pushin g i t gentl y wit h th e finge r
wil l caus e i t t o sin k slightly . Increasin g th e forc e o n
i t wil l caus e i t t o sin k deeper .
— If th e los t motio n assembl y doe s no t mov e
smoothly , replac e it .
Pus h
LOS T MOTIO N ASSEMBL Y
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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 diamete r o f 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 EGAUG E
3. Measur e insid e diamete r o f rocke r arm , an d chec k fo r
out-of-roun d condition .
Rocke r 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 mfac 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:
• D o no t rotat e th e camshaf t durin g inspection .
• Remov e th e rocke r arm s an d rocke r shafts .
1 . Pu t th e camshafts , th e camshaf t holder s an d holde r
plate s o n th e cylinde r head , an d the n tighte n th e bolt s
t o th e specifie d torque .
NOTE : Appl y clea n engin e oi l t o 8 m m bol t threads .
Specifie d torque :
8 m m x 1.2 5 m m bolts :
22N- m (2. 2 kg-m , 1 6 Ib-ft )
6 m m x 1. 0 m m bolts :
10N- m (1. 0 kg-m , 7 Ib-ft )
CAMSHAF T HOLDE R BOLT S TORQU E
SEQUENCE
FRONT :
2. Sea t th e camshaf t b y pushin g i t towar d th e lef t en d o f
cylinde r head .
3 . Zer o th e dia l indicato r agains t th e lef t end , the n pus h
th e camshaf t bac k an d forth , an d rea d th e en d play .
Camshaf t En d Play :
Standar d (New) : 0.05—0.1 5 m m
(0.002—0.006 in)
Servic e Limit : 0. 5 m m (0.0 2 in )
4 . Remov e th e bolts , the n remov e th e camshaf t holder s
fro m th e cylinde r head .
— Lif t th e camshaft out o f th e cylinde r head , wip e i t
clean , the n inspec t th e lif t ramps . Replac e th e
camshaft if lobe s ar e pitted , scored , o r excessivel y
worn.
— Clea n th e camshaf t bearin g surface s i n th e cylin -
de r head , the n se t th e camshaf t bac k in place .
— Inser t a plastigag e stri p acros s eac h journal.
5 . Instal l th e camshaf t holders , an d the n tighte n th e
bolt s t o th e specifie d torqu e a s show n i n th e lef t
colum n o n thi s page .
6 . Remov e th e camshaf t holder s an d measur e wides t
portio n o f plastigag e o n eac h journal .
Camshaft-to-Holde r Oi l Clearance :
Standar d (New) :
0.050-0.08 9 mm
(0.002-0.00 4 in)
Servic e Limit : 0.1 5 m m (0.00 6 in )
PLASTIGAG E STRI P
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7. If camshaft-to-holder oil clearance is out of

tolerance:

— And camshaft has already been replaced, you

must replace the cylinder head.

— If camshaft has not been replaced, first check to-

tal 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.

8. Check cam lobe height wear.

Cam Lobe Height Standard (New):

M/T

A/T
Check this area for wear.

Cam position

P: Primary M: Mid S: Secondary

FRONT BANK

REAR BANK
CYLINDER

NUMBER

EXHAUST

INTAKE

CYLINDER

NUMBER

INTAKE

EXHAUSTProCarManuals.com

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 re -
move d s o tha t eac h ite m ca n b e reinstalle d in it s origina l
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
SOCKE T
2. Instal l th e sprin g compressor . Compres s th e sprin g
an d remov e valv e keeper .
VALVE SPRIN G
COMPRESSO R
ATTACHMENTEXTENSION07MAF-PR9010 A
VALVE SPRIN G
COMPRESSO R
ATTACHMENT07757 - PJ1010 A
VALVE SPRIN G COMPRESSO R(Commercially available )Snap-on CF71 1 o r equivalen t
3. Instal l th e specia l too l a s shown .
VALVE SEA L VALV
E GUID E SEA L REMOVE R
(Commerciall y available )
LISL E P/ N 5790 0 o r KD335 0
SEALPULLE R
4. Remov e th e valv e guid e seal .
VALV E GUID E SEA L REMOVE R
(Commerciall y available )
LISL E P/ N 5790 0 o r KD335 0
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