NANO ePAS

110

ENGINE 273 MPFI

VALVE SEATS

•

Check valve seat height with respect to cylinder

head mating surface.

•

Replace valve seat inserts if they are worn out

beyond specified limit.

•

Cut exhaust and inlet valve seats with a 45° cutter.

NOTE

Valve seat must be absolutely faultless and without

any chatter marks.

•

If necessary lap valve seats to a smooth and even

finish by using suitable hand pump grinder or a

lapping paste and valve itself.

•

Smear valve seat with carbon blue. Install valve in

guide and turn it slowly under axial pressure.

•

Distance between narrow diameter of valve face to

contact line should be minimum.

•

Check for leakages through valve seat by pouring

gasoline on valve head. Gasoline must not seep

past valve seat.

Valve Seat Inserts

•

For removing valve seat inserts from cylinder head

use a suitable boring machine. Bore old insert thin

(about 0.5 mm thickness) and then pry it out.

•

Alternatively use a suitable turning tool to cut

an annular groove into valve seat insert and then

pull it out with a suitable puller. In order to avoid

damaging machined cylinder head mating surface

with crank case, place any soft protective

sheetmetal under supports ofpuller.

•

Measure valve seat insert bore in cylinder head.

•

If boring and prying is done carefully without

damaging valve seat insert bore in cylinder head,

fitment of an over size valve seat insert will not be

necessary.

•

All specified dimensions should be strictly

maintained to ensure proper interference of valve

seat insert in its bore.

•

Clean the valve seat insert and its bore in cylinder

head thoroughly.

Just before installation :

•

Place valve seat insert in a mixture of Methanol

and dry ice for about 20-30 minutes to bring its

temperature down to

150°C.

•

Heat cylinder head to approximately 80°C in water

bath.

•

Install valve seat insert in cylinder head bore

quickly by using mallet.

•

Machine valve seat in cylinder head.

VALVE SEAT INSERT THICKNESS

INLET

EXHAUST

6 mm

VALVE SEAT INSIDE DIAMETER IN INSERT

INLET

EXHAUST

28. 7± 0.1 mm

23.5 ± 0.1 mm

VALVE SEAT INSERT & BORE DIA. IN

CYLINDERHEAD

Stage Valve seat insert Valve seat insert

bore diameter in outside diameter

cyl. Head (mm)

(mm)

Inlet

Normal

34.1 H7

34.1 Z6

Normal 1

34.4 H7

34.4 Z6

Exhaust

Normal

31.5 H7

31.55 X7

Normal 1

31.8 H7

31.85 X7