Lexus SC300 / Lexus SC400. Manual — part 350

22. ADJUST VALVE CLEARANCE
(a) Remove the adjusting shim.

•

Turn the crankshaft so that the cam lobe of the camshaft
on the adjusting valve upward.

•

Position the hole of the adjusting shim facing the spark
plug side.

•

Using SST (A), press down the valve lifter and place
SST (B) between the camshaft and valve lifter flange.
Remove SST (A).

SST 09248–05410, 09248–05021

NOTICE: The valve lifter is made of aluminum, which is easily

scratched. So when setting SST (B), take care not to scratch

the face of the valve lifter.

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EG–21

•

Using compressed air and a magnetic finger, remove
the adjusting shim by blowing air into the shim hole.

HINT: Remove the adjusting shim from the intake manifold
side.

NOTICE: Do not drop the adjusting shim into portions A and

B. If dropped into portion A, the adjusting shim will pass

through the cylinder head and cylinder block into the oil pan.

If dropped into portion B, the adjusting shim cannot be recov-

ered without removing the exhaust camshaft.

EG–22

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(b) Determine the replacement adjusting shim size by following

the Formula or Charts:

•

Using a micrometer, measure the thickness of the
removed shim.

•

Calculate the thickness of a new shim so that the valve
clearance comes within specified value.

T

. …

Thickness of removed shim

A

. …

Measured valve clearance

N

. …

Thickness of new shim

Intake:

N = T + (A – 0.20 mm (0.008 in.))

Exhaust:

N = T + (A – 0.30 mm (0.012 in.))

•

Select a new shim with a thickness as close as possible
to the calculated value.

HINT: Shims are available in 33 sized in increments of 0.025
mm (0.0010 in.) from 2.50 mm (0.0984 in.) to 3.30 mm
(0.1299 in.)

(c) Install a new adjusting shim.

•

Place a new adjusting shim on the valve lifter.

•

Using SST (A), press down the valve lifter and remove
SST (B).

SST 09248–05410, 09248–05021

(d) Recheck the valve clearance.

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ENGINE MECHANICAL

EG–23

V01867

EG–24

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