Isuzu N-Series. Manual

The 4JB1 Model engine employs a square troidal type
combustion chamber provided with a fence around it.
These designs employed allow a superior fuel economy
over a wide range of driving conditions.
The 4JG2 Model engine employs, for its combustion
chamber, the RECARD Comet V Type swirl combustion
chamber which provides a superior driving perfor-
mance, fuel economy and silent combustion over a wide
range of driving conditions.
For the cylinder head gasket steel sheets, laminated
steel sheets are employed.
Three grades of the gaskets according to the piston
head projection measured from the cylinder block are
employed to minimize the fluctuation of the engine com-
pression ratio.
The Angular Tightening Method is employed to tighten
the cylinder head fixing bolts, connecting rod fixing bolts
and flywheel fixing bolts.
The chrome-plated steel dry type (Chromard) cylinder
liners provide the highest durability.
Auto-thermic pistons with cast steel struts are used to
reduce thermal expansion and resulting engine noise
experienced while the engine is cold.
The tufftrided crankshaft has a long service life. Be-
cause it is tufftrided, it cannot be reground.
The crankshaft main bearings and the connecting rod
bearings are of aluminum alloy. These bearings are es-
pecially vulnerable to foreign materials such as metal
scraps. It is very important to keep the oil ports and other
related surfaces clean and free of foreign materials.
The tufftriding treatment (nitriding treatment) of the
crankshaft for the increased strength eliminates the re-
grinding of crankpins and journals.
An oiling jet device for piston cooling is provided in the
lubricating oil circuit which runs through the check valve
from the cylinder block oil gallery.
Take care not to damage the oiling jet when removing or
installing the piston and the connecting assembly.
The 4JG2 engine use a single spring pintle type injection
nozzle.
The 4JB1 Model employs a direct injection type engine
provided with a nozzle with four holes, which makes it
possible to obtain an excellent mixing ratio of intake air
and fuel spray.
4JB1-TC engine has two springs injection nozzle sys-
tem for efficient control.
The turbocharger increase air intake efficiency, the re-
sults in increased engine power, reduced fuel consump-
tion and minimal engine noise.
Turbocharger rotating parts operate at very high speeds
and temperatures. The parts materials have been care-
fully selected and machined to extremely high precision.
The 4JB1 Model engine employs the QOS II preheating
system which features a quick-on glow to control the
glow time and the afterglow time by the thermometer.
The 4JG2 engine employs the QOS III system which al-
lows the most suitable starting conditions for the glow
time to change according to the engine water tempera-
ture, and the optimum for the glow time to change ac-
cording to the engine water temperature, and the

optimum changes according to the water temperature
immediately after the start of the engine.
The belt-driven type timing drive belt of the 4JG2 Model
engine is a very important functional part, and requires
the specified maintenance.

Isuzu N-Series. Manual - part 578