Infiniti G20 (P11). Manual - part 389

AEM343

Use a depth gauge to measure the distance between the mount-
ing surface of the cylinder head spring seat and the valve stem end.
If the distance is shorter than the specified valve, repeat step 5
above to adjust it.
If it is longer, replace the valve seat with a new one.

Valve seat resurface limit:

42.74 - 43.26 mm (1.6827 - 1.7031 in)

SEM188A

VALVE DIMENSIONS

NCEM0019S12

Check dimensions of each valve. Refer to SDS, EM-69.
When valve head has been worn down to 0.5 mm (0.020 in) in
margin thickness, replace valve.
Grinding allowance for valve stem tip is 0.2 mm (0.008 in) or
less.

SEM288A

VALVE SPRING

NCEM0019S13

Squareness

NCEM0019S1301

Measure dimension “S”.

Out-of-square “S”:

Less than 2.1 mm (0.083 in)

If it exceeds the limit, replace spring.

EM113

Pressure

NCEM0019S1302

Check valve spring pressure at specified spring height.

Pressure:

Standard

519 - 571 N (52.9 - 58.2 kg, 116.7 - 128.4 lb) at 27.0
mm (1.063 in)

Limit

More than 491.8 N (50.16 kg, 110.56 lb) at 27.0 mm
(1.063 in)

If it exceeds the limit, replace spring.

SEM935C

HYDRAULIC LASH ADJUSTER

NCEM0019S14

Check contact and sliding surfaces for wear or score.

IDX

CYLINDER HEAD

Inspection (Cont’d)

EM-41

SEM936C

Check diameter of lash adjuster.

Outer diameter:

16.980 - 16.993 mm (0.6685 - 0.6690 in)

SEM084D

Check lash adjuster guide hole diameter.

Inner diameter:

17.000 - 17.020 mm (0.6693 - 0.6701 in)

Standard clearance between lash adjuster and adjuster
guide hole:

0.007 - 0.040 mm (0.0003 - 0.0016 in)

SEM063G

ROCKER ARM, SHIM AND ROCKER ARM GUIDE

NCEM0019S15

Check contact and sliding surfaces of rocker arms, shims and
rocker arm guides for wear or score.

Assembly

NCEM0020

CAUTION:

When installing rocker arms, camshaft and oil seal, lubri-
cate contacting surfaces with new engine oil.

When tightening cylinder head bolts, camshaft sprocket
bolts and camshaft bracket bolts, lubricate bolt threads
and seat surfaces with new engine oil.

AEM116

If a hydraulic lash adjuster is kept on its side, there is a
risk of air entering it. When hydraulic lash adjusters are
removed, stand them straight up or soak them in new
engine oil.

Do not disassemble hydraulic lash adjusters.

Attach tags to lash adjusters so as not to mix them up.

CYLINDER HEAD

Inspection (Cont’d)

EM-42

SEM595D

Install valve component parts.

Install valves, noting their identification marks as indi-
cated in the table below.

Identification mark

Intake valve

2J3

Exhaust valve

J21

SEM085D

Always use new valve oil seal.
Refer to EM-28.

Before installing valve oil seal, install valve spring seat.

Install valve spring (uneven pitch type) with its narrow
pitched side (paint mark) toward cylinder head side.

After installing valve components, use plastic hammer to
lightly tap valve stem tip to assure a proper fit.

SEM093D

Check hydraulic lash adjusters.

Push on the rocker arm above the hydraulic lash adjuster. If it
moves 1 mm (0.04 in) or more, there is air in the high pressure
chamber of hydraulic lash adjuster.
Noise will be emitted from hydraulic lash adjuster if engine is
started without bleeding air.

AEM117

Remove hydraulic lash adjuster and dip in a container filled
with new engine oil. While pushing plunger as shown in figure,
lightly push check ball using a thin rod. Air is completely bled
when plunger no longer moves.

Air cannot be bled from this type of lash adjuster by running
engine.

SEM057G

Remove camshafts, rocker arms and shims. For future
reference, identify each shim with the cylinder it was removed
from. Since the shims are reusable, it may not be necessary
to replace all of the existing shims.

IDX

CYLINDER HEAD

Assembly (Cont’d)

EM-43

SEM364D

Before attempting any measurement, make sure the valve,
valve spring, collet, retainer and rocker arm guide are properly
installed in the head.

Always replace rocker arm guide with a new one.

CAUTION:

Install parts in their original positions.

AEM201

Install the J38957-1 gauge plate into the tapped holes at the
cam journals and secure it to the head using two of the hex
bolts supplied with the kit. (The two remaining bolts are
spares.)

AEM202

AEM236

Place the J38957-2 collar on the J38957-8 dial indicator. Make
sure the dished side of the collar is facing “up” (toward the dial
indicator). Secure the collar to the dial indicator by tightening
the set screw in the collar.

Place the indicator and collar over #1 cylinder intake valve
shim side. Slide the tip of the dial indicator through the access
hole and place it on the end of the valve stem. While resting
the dial indicator collar on the gauge plate, “zero” the dial indi-
cator.

Move the dial indicator and collar to the adjacent hole in the
gauge plate and place the tip of the indicator in the center of
the rocker arm guide. Write down the dial indicator reading.
This measured distance between the valve stem end and the
contact surface of the rocker arm guide is the “T

” dimension.

Match the measured “T

” dimension (in inches) to the available

shim chart (in millimeters). Refer to SDS, EM-71. (The “T

”

dimension is equivalent to the thickness and size designation
of the valve shim.) Select the closest size shim to the mea-
sured “T

” dimension. For example, if the measured “T

”

dimension is 0.1152 in, use a 2.925 mm (0.1152 in) shim.
Shims are available in 17 different thicknesses ranging from
2.800 mm (0.1102 in) to 3.200 mm (0.1260 in) and increase in
increments of 0.025 mm (0.0010 in).

CYLINDER HEAD

Assembly (Cont’d)

EM-44

Content .. 387 388 389 390 ..