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56
FIAT· 850 PASSENGER CARS
Checking Water Seal.
11
16 5
II
18
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Valve seats in head should show no evidence of
pitting at valve contact area; otherwise grind seats
as follows.
Insert pilot A. 94015 in valve guide; select the
pilot which will warrant least possible clearance.
Position taper grindwheel A. 94084 on spindle
A. 94069.
Slide coil spring into spindle.
Install spindle on grinder Ap. 5025.
Checking
~
and Reseating Valve Seats.
Submit the head to the following leakage lest of
coolant jackets:
Fit components of fixture A. 60081 to head.
- Connect hand pump Ap. 5048 to cock.
- Heat water in tank to 185
0
to 194
0
F (85
0
to
90' C).
- Pump water into head to build up a pressure
of 28.5 to 42.7 psi (2 to 3 kg/ern'); at this pressure
no leakage should occur.
The presence of cracks or fractures
will
be
indicated by the pressure gauge pointer moving
back to zero and the water leaking out of the head.
H so, renew the head directly.
against the following clearances between gauge
shoulder and head face:
- engine lOOG.OOO . .
.01" (0.25 rnrn) max.
- engine lOOG.OO2
.04" to .05" (I to 1.25 rnrn)
Should head undercutttng exceed reconunended
limits, replace cylinder head
by
a new one.
After grinding, wash the head thoroughly to
remove
all
stock and abrasive residues.
Fig. 88 - Checking cylinder head on surface plate.
Coat surface plate with a
filin
of lampblack and
slide about the head on the surface plate.
The lampblack pattern should be uniformly spread
over the whole head face (fig. 88).
If
not so distortion is evident and the head must
be ground on surface grinder M. 1020.
Use care to remove as little stock as possible.
With gauge A. 95650 check the depth of com-
bustion chambers (fig. 89) to make sure that they
have not been reduced too much.
Set the gauge at center of combustion chamber
(see fig. 89) and using feeler A. 95113, check
Checking and Grinding Head Bottom
Face.
Fig. 90 • Critical dimensions (metric) of valve seats In head.
Fig. 89 • Checking depth of combustion ehamber•.
1.
Glluge A. 95650. - 2, Feeler A. 95113. - 3. Head holding fixture
A. 60041.
INTAKE
EXHAUST
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