C-Series Book - Industrial Engine Service

7 ENGINE OVERHAUL
7
CYLINDER HEAD
The cylinder head is an iron alloy casting
with chrome nickel replaceable intake and
exhaust valve inserts.
Maintenance service and adjustments can
be readily performed, as the head can be
easily removed without disturbing any other
major engine parts. In the event the engine
develops low compression, loss of power, is
diffi cult to start, or has a combustion knock
due to carbon deposits, the head should be
removed for inspection.
CYLINDER HEAD
INLET
PORT
VALVE
GUIDES
EXHAUST
PORT
INTAKE
VALVE
VALVE
SEAT
INSERTS
EXHAUST
VALVE
DISASSEMBLY OF CYLINDER HEAD
1. Remove cylinder head cover. Disconnect
fuel line from carburetor. Disconnect
throttle rod at carburetor.
2. Remove cylinder head stud nuts and lift
off the cylinder head. Place combustion
chamber over a suitable block to hold
valves in closed position.
3. With a suitable lever (a 3/8" U-shaped rod is
satisfactory) under the rocker arm, depress
the valve spring to release the valve spring
lock retainers. The valve spring washers
and valve springs can be removed.
4. Clean all parts in solvent or fuel oil
to remove carbon, gum, and varnish
deposits. If the valves or valve seats
are severely burned, they should not be
reground, since the metal behind the burn
has probably lost its original properties.
Valves that are warped or have reduced
diameter at the valve stem should be
discarded and replaced with new valves.
5. When refacing the valves, the maximum
face runout in reference to the valve
stems should not exceed .002" (total
indicator readings) and only enough metal
should be removed to produce a bright
face and a continuous margin.
REFACING THE VALVES
Valves should be ground to a 45° seat angle.
Grind the seat with a 45° grinding wheel. Because
the valve guide is used to pilot the grinder, this
procedure must be attempted only when the
valve guides are clean and in good condition.
VALVE REFACING
RIGHT
WRONG
Hold valve face and seat runout to .002
inch and maintain sufficient margin as
illustrated above. Excessive runout or
insufficient margin may lead to early
valve failure.
WRONG
1°
RIGHT
Maintain a valve seat width of 7/64" to 1/8"
by grinding the outer edge of the seat on a 75
degree angle. Do not grind the seat bore to
narrow the seat, as this moves the center of the
seat too near the valve edge. Discard valves
that have been refaced to point where the edge
of the valves become less than 3/64".
1°
1-800-331-3662 ARROW ENGINE COMPANY
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