Specifications

PART 1-1-GENERAL ENGINE SERVICE
Ml
However, the compression of all
cylinders should be uniform within
10 pounds.
A reading of more than the allow-
able tolerance above normal indi-
cates excessive deposits in the cyl-
inder.
A reading of more than the allow-
able tolerance below normal indi-
cates leakage at the cylinder head
gasket, piston rings, or valves.
A low even compression in two
adjacent cylinders indicates a cylin-
der head gasket leak. This should be
checked before condemning the rings
or valves.
To determine whether the rings or
the valves are at fault, squirt the equi-
valent of a tablespoon of heavy oil
into the combustion chamber. Crank
the engine to distribute the oil and
repeat the compression test. The oil
will temporarily seal leakage past the
rings. If approximately the same
reading is obtained, the rings are
satisfactory, but the valves are leak-
ing. If the compression has increased
10 pounds or more over the original
reading, there is leakage past the
rings.
During a compression test, if the
pressure fails to climb steadily and
remains the same during the first two
successive strokes, but climbs higher
on the succeeding strokes, or fails to
climb during the entire test, it indi-
cates a sticking valve.
CLEANING, INSPECTION, AND RECONDITIONING
INTAKE MANIFOLD
Clean the manifold in a suitable
solvent. Dry it with compressed air.
Inspect the manifold for cracks,
leaks, or other defects that would
make it unfit for further service. Re-
place all studs that are stripped or
otherwise damaged. Remove all fil-
ings and foreign matter that may
have entered the manifold as a re-
sult of repairs.
On the 352 and 390 V-8 engines,
check the baffle plate on the under-
side of the manifold for looseness
and be sure the maze screen is in
place. Clean off any varnish.
EXHAUST MANIFOLDS
Inspect the manifolds for cracks,
leaks, or other defects 'hat would
make them unfit for further service.
On the right exhaust manifold of
the 352 and 390 V-8 engines, make
sure the automatic choke air inlet
and outlet holes are completely open
and the cover does not leak. Blow
out the automatic choke air heat tube
with compressed air.
VALVE ROCKER ARM
SHAFT ASSEMBLY
CLEANING AND INSPECTION
Clean all the parts thoroughly.
Make sure all oil passages are open.
Check the clearance between
each rocker arm and the shaft by
checking the ID of the rocker arm
bore and the OD of the shaft. If the
clearance between any rocker arm
and the shaft exceeds the wear limit,
replace the shaft and/or the rocker
arm. Inspect the shaft and the rocker
arm bore for nicks, scratches, scores,
or scuffs.
Inspect the pad at the valve end
of the rocker arms for a grooved
radius.
Check for broken locating
springs.
On engines with mechanical or
silent lash valve lifters, check the
rocker arm adjusting screws and the
push rod end of the rocker arms for
stripped or broken threads, and the
ball end of the adjusting screw for
nicks, scratches, or excessive wear.
Inspect the oil tubes for cracks or
sharp bends.
On the Mileage Maker Six, in-
spect the eccentric for abnormal
wear in the area of contact with the
valve stem tip and the rocker arm
bearing recess. Inspect the eccentric
bearing recess machined in the
rocker arm. Evidence of wear in this
area can best be determined by
measuring the length of the inner
slot or relief area machined in the
cavity (Fig. 9). Using a divider,
measure the length of the slot. Take
the measurement perpendicular to
the arm axis. If the slot length has
decreased to or below the recom-
mended minimum, replace the arm.
REPAIRS
Dress up minor surface defects on
the shaft and in the rocker arm bore
with a hone.
On engines with mechanical or
silent lash valve lifters, if the pad at
the valve end of the rocker arm has a
grooved radius, replace the rocker
arm. Do not attempt to true this
surface by grinding.
PUSH RODS
INSPECTION
Check the ends of the push rods
for nicks, grooves, roughness, or ex-
cessive wear.
The push rods can be visually
checked for straightness while they
are installed in the engine by rotat-
ing them with the valve closed.
SEE
SPECIFICATIONS
A1552-A
FIG. 9—Silent Lash Rocker
Measurement
They also can be checked with a
dial indicator (Fig. 10).
REPAIRS
If the runout exceeds the maxi-
mum limit at any point, discard the
rod. Do not attempt to straighten
push rods.
CYLINDER HEADS
CLEANING
With the valves installed to pro-
tect the valve seats, remove deposits
from the combustion chambers and
valve heads with a scraper and a
wire brush. Be careful not to damage
the cylinder head gasket surface.
After the valves are removed, clean
the valve guide bores with a valve
Dial Indicator
Holding Fixture
PUSH
A1003-A
FIG. 10—Push Rod Runout