Technical data

CONSTRUCTION AND SERVICING OF CYLINDER HEAD
CONSTRUCTION
1. Cylinder Head
The cylinder head is an overhead valve head produced from a high rigidity special cast iron
having an excellent cool-effect. Intake end exhaust ports are of a cross-flow type which insures
good 'intake and exhaust efficiency. The combustion chamber is a swirl chamber produced from
heat resisting steel and is press-fitted in the cylinder head. This chamber, therefore, requires no
disassembly. Intake and exhaust valve guides are made of sintered alloy and are commonly
usable in either ports. The valve guides are oil-impregnated to provide greater wear resistance.
2. Cylinder Head Gasket
The cylinder head gasket is an alloy-asbestos gasket
and is fitted with stainless steel sheet grommets around
the bores to provide greater heat and pressure
resistance. Both sides of the gasket are coated with a
sealant and therefore does not require further applica-
tion of the sealant. New gaskets are made of carbon
called "grafoil".
3. Valve and Valve Spring
The intake valve is a heat-resisting steel valve having a
large diameter head to provide great intake efficiency.
The exhaust valve has a special heat-resisting steel
head welded to the valve stem so the valve may have
adequate resistance to high temperatures.
Valve springs are made of spring steel and are closed at the upper end. They carry a red enamel
mark on the upper part (rocker arm side) for easy identification of the upper and lower ends. The
retainer and retainer lock are commonly usable with intake and exhaust valves. In the top of the
valve guide, a valve stem seal is fitted to prevent downward seepage of oil along the valve stem.
4. Rocker Arm, Rocker Shaft and Stay
Rocker arms are make of special cast iron and are gas-carburized on the entire surface. Each arm
has an oil hole in the upper part. The rocker arm shaft is produced from a carbon steel tube, the
interior of which forms a lubricant passage. The rocker arm area of the shaft is
induction-hardened. The rocker shaft stay is an aluminum alloy casting. The rear stay is provided
with an oil hole into which the oil from the head flows for lubrication of the rocker shaft.
5. Crankcase Ventilating System
The crankcase ventilating system leads blow-by fumes from the cylinder block up into the rocker
without discharging the fumes out into the atmosphere. The fumes flow into the cover through
tappet holes and push rod holes and further into the cylinders for recombustion through the air
breather hose (rubber hose) and inlet pipe.