ACURA NSX 1997 Service Repair Manual

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) .
ProCarManuals.com

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
ProCarManuals.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
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)
ProCarManuals.com

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

A/T:

Intake Valve Dimensions

A Standard (New): 34.9 - 35.1 mm

(1.374 - 1.382 in)

B Standard (New):

C Standard (New):

C Service Limit:

D Standard (New):

D Service Limit:
111.10-111.40 mm

(4.374 - 4.386 in)

5.475-5.485 mm

(0.2156-0.2159 in)

5.445 mm (0.2144 in)

1.05—1.35 mm

(0.041-0.053 in)

0.85 mm (0.033 in)

Exhaust Valve Dimensions

A
Standard (New):
29.9-30.1
mm

(1.177-1.185 in)

109.60-109.90
mm

(4.315-4.327 in)

5.45-5.46
mm

(0.2146-0.2150 in)

5.42 mm (0.2134 in)

1.65-1.95
mm

(0.065-0.077 in)

1.45 mm (0.057 in)
B Standard (New):

C Standard (New):

C Service Limit:

D Standard (New):

D Service Limit:ProCarManuals.com

Cylinder Head s
Warpag e
NOTE: I f camshaft-to-holde r oi l clearance s (se e page s
6-35 , 6-36 ) ar e no t withi n specification , th e cylinde r hea d
canno t b e resurfaced .
I f camshaft-to-holde r oi l clearance s ar e withi n specifica -
tions , chec k th e cylinde r hea d fo r warpage .
• I f warpag e i s les s tha n 0.0 5 m m (0.00 2 in ) cylinde r
head resurfacin g i s no t required .
• I f warpag e i s betwee n 0.0 5 m m (0.00 2 in ) an d 0. 2
mm (0.00 8 in) , resurfac e cylinde r head .
• Maximu m resurfac e limi t i s 0. 2 m m (0.00 8 in ) base d
on a heigh t o f 1 51 m m (5.94 5 in) .
PRECISIO N STRAIGH T EDG E
Measur e alon g edges , an d thre e way s acros s center .
Cylinde r Hea d Height :
Standar d (New) : 150.9 5 - 151.0 5 m m
(5.94 3 - 5.94 7 in )
ProCarManuals.com

Valve Seat s
Reconditionin g
1. Rene w th e valv e seat s i n th e cylinde r hea d usin g a
valv e sea t grinder .
NOTE : I f guide s ar e wor n (se e pag e 6-41 ), replac e
the m (se e pag e 6-42 ) befor e grindin g th e valv e seats .
2 . Carefull y grin d a 45 ° seat , removin g onl y enoug h
materia l t o ensur e a smoot h an d concentri c seat .
3 . Beve l th e uppe r edg e o f th e sea t wit h th e 30 ° stone .
Beve l th e lowe r edg e i t tw o angles .
Firs t grin d th e edg e wit h th e 60 ° stone , the n grin d
th e botto m edg e wit h th e 67.5 ° stone .
Chec k widt h o f sea t an d adjus t accordingly .
4 . Mak e on e mor e ver y ligh t pas s wit h th e 45 ° ston e t o
remov e an y possibl e burr s cause d b y th e othe r
stones .
Valv e Sea t Width :
Standar d (New) :
Intak e 0.8 0 - 1.0 0 m m (0.03 1 - 0.03 9 in )
Exhaus t 1.2 5 - 1.5 5 m m (0.04 9 - 0.06 1 in )
Servic e Limit :
Intak e 1. 5 m m (0.05 9 in )
Exhaus t 2. 0 m m (0.07 9 in )
SEA T WIDT H
5. Afte r resurfacin g th e seat , inspec t fo r eve n valv e
seating : Appl y Prussia n Blu e compoun d t o th e valv e
face , an d inser t valv e i n origina l locatio n i n th e head ,
the n lif t i t an d sna p i t close d agains t th e sea t sever -
a l times .
ACTUA L
SEATIN G
SURFAC E
VALVESEAT
PRUSSIA N BLU E COMPOUN D
6. Th e actua l valv e seatin g surface , a s show n b y th e
blu e compound , shoul d b e centere d o n th e seat .
• I f i t i s to o hig h (close r t o th e valv e stem) , yo u
mus t mak e a secon d cu t wit h th e 60 ° ston e t o
mov e it down , the n on e mor e cu t wit h th e 45 °
ston e t o restor e sea t width .
• I f i t i s to o lo w (close r t o th e valv e edge) , yo u mus t
make a secon d cu t wit h th e 30 ° ston e t o mov e
it up , the n on e mor e cu t wit h th e 45 ° ston e t o
restor e sea t width .
NOTE : Th e fina l cu t shoul d alway s b e mad e wit h
th e 45 ° stone .
7 . Inser t intak e an d exhaus t valve s i n th e hea d an d
measur e valv e ste m installe d height .
Valv e Ste m Installe d Heigh t (Intak e an d Exhaust) :
Standard (New) : 41.55-42.3 5 m m
(1.6358-1.667 3 in )
Servic e Limit : 42.43 5 m m (1.670 7 in )
VALV E STE M
INSTALLE D HEIGH T
8. I f valv e ste m installe d heigh t i s ove r th e servic e limit ,
replac e th e valv e an d recheck . I f stil l ove r th e servic e
limit , replac e th e cylinde r head ; th e valv e sea t i n th e
hea d is to o deep .
ProCarManuals.com

Valve Guides

Valve Movement

Measure the guide-to-stem clearance with a dial indicator

while rocking the stem in the direction of normal thrust

(wobble method).

Intake Valve Stem-to-Guide Clearance:

Standard (New): 0.05 — 0.11 mm

(0.002 — 0.004 in)

Service Limit: 0.16 mm (0.006 in)

Exhaust Valve Stem-to-Guide Clearance:

Standard (New): 0.10 — 0.16 mm

(0.004 — 0.006 in)

Service Limit: 0.22 mm (0.009 in)

Valve extended 10 mm out from seat.

If measurement exceeds the service limit, recheck

using a new valve.

If measurement is now within the service limit,

reassemble using a new valve.

If measurement still exceeds limit, recheck using

alternate method below, then replace valve and

guide, if necessary.
NOTE: An alternate method of checking guide to

stem clearance is to subtract the O.D. of the valve

stem, measured with a micrometer, from the I.D. of

the valve guide, measured with an inside microme-

ter or ball gauge.

Take the measurements in three places along the

valve stem and three places inside the valve guide.

The difference between the largest guide measure-

ment and the smallest stem measurement should

not exceed the service limit.

Intake Valve Stem-to-Guide Clearance:

Standard (New): 0.025 — 0.055 mm

(0.001 — 0.002 in)

Service Limit: 0.08 mm (0.003 in)

Exhaust Valve Stem-to-Guide Clearance:

Standard (New): 0.05 — 0.08 mm

(0.002 — 0.003 in)

Service Limit: 0.11 mm (0.004 in)ProCarManuals.com