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66
FIAT· 850 PASSENGER CARS
Fig. 11& - Reaming tappet seats in crankcase.
1. Reamer handle. - 2. Reamer A. 90318/1.
PUSH RODS
The push rods controlling rockers should not be
distorted and their ball seat which contacts the
rocker should not be rough nor show signs
Fig. 117 - Timing marks on drive and driven sprockets.
Chain stretchers should always be turned outward, as shown in
figure.
of seizure; otherwise replace push rods
by
new
ones.
The opposite end contacting the tappet, too,
should not be too much worn or pitted; renew the
push rod,
if
required.
VALVE TIMING
The correct valve timing is obtained when the
timing marks on sprockets are indexing as shown
in fig. 117.
To line up the timing marks on sprockets, proceed
as follows:
- insert the drive sprocket on the front end of
crankshaft;
- install the driven sprocket on camshaft and
tum it about until the mark machined on its outskirts
is in line with the notch on the drive sprocket;
- without moving the camshaft, take out the
driven sprocket, and mesh the timing chain with
the sprockets; reinstall the driven sprocket and
chain, using care that the timing marks are index-
ing (fig. 117); lock the crankshaft and camshaft by
placing tool A. 60282 on the flywheel; use a torque
wrench and draw up the driven sprocket screw
with 36.2 it.lbs (5 kgm) of torque, then bend down
the lock plate.
Should the necessity arise to check whether the
timing marks are stamped in the right 'place and
consequently the correct valve timing has been
obtained, proced as follows:
- affix the sector scale A. 95694 on crankcase;
- fit the crank A. 60186 with the item A. 60186/1
on the flywheel;
- temporarily set the tappet clearance of cylinder
No. I at .0148" (0.375 nun);
- using the crank, tum about the flywheel until
the cylinder No. 1 begins the compression stroke,
that
is
the intake valve is just on the way of open-
ing: at this point the flywheel mark (showing T.D.C.
of cylinder Nos. I and 4) should register 160 before
T.D. C.; go on cranking the flywheel until its mark
is indexing with the zero sign on sector scale;
TAPPET· TAPPET SEAT FITTING SPECIFICATIONS
SIZES
Crankcase Seat Bore
Tappet Diameter
Fits of New Parts
Standard.
.5516" to .5523/1
.5512" to .5505"
.0004" to .0018"
(14.010 to 14.028 nun)
(14.000 to 13.982 rom)
(0.010 to 0.046 nun)
.0020" (0.05 nun) oversize
.5535" to .5542"
.5531" to .5524"
.0004" to .0018/1
.
(14.060 to 14.078 nun)
(14.050 to 14.032 nun)
(0.010 to 0.046 mm)
.0040" (0.10 nun) oversize
.5555" to .5562"
.5551" to .5544"
.0004" to .0018"
(14.110 to 14.128 rnm)
(14.100 to 14.082 nun)
(0.010 to 0.046 mm)
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