GENERAL INFORMATION - General 1-1
GENERAL
The 5R model en ine is desi ned based on the 3R model en ine with the various
different features such as increased displacement, modified combustion chambers
and manifold ports, raised power and torque, to ether with improved durability
and reliability. This en ine is equipped on the Toyota Grown, Stout, Dyna and
Li ht Bus series.
The 3R-B model en ine was also developed from the 3R model en ine by im
provin the reliability.
The 3R-C model en ine is incorporated with the crankcase ventilation and the
exhaust emission control systems on the 3R-B model en ine.
These en ines are equipped on the Toyota Corona series.
The construction of all en ines is the same basically, but their specification are
sli htly different from each other. Therefore, the eneral information is described
in accordance to the 5R model en ine, and different features only will be des
cribed for the 3R-B and 3R-C model en ines.
The 5R, 3R-B and 3R-C model en ines are of four-cylinder in-line, overhead
valve, water-cooled type.
The cylinder head is of a cast iron, and incorporates a bath-tub type combustion
chambers.
The cylinder block is also of durable cast iron, and incorporates the oil passa e
within the cylinder block front at the ri ht side to lubricate the valve rocker arm
mechanism.
The pistons are of a low-expansion type which is of aluminum silicone alloy with
excentric finished sli htly lar er at the ri ht an le to the piston pin bore. More
over, these pistons are cast in with a steel rin under the oil rin roove to
minimize the heat expansion of the piston.
The piston rin s are of two compression rin s and one oil rin for each piston ,
and both rin s are chrome-plated for durability.
The piston pin is off-sett 1.0 mm (0.039M) towards the camshaft side which
contributes to smooth en ine operation, and is secured onto the piston with snap
rin s at both ends of the piston pin.
The connectin rods are of for ed steel with "H" beam section, and bronze
piston pin bushin s are installed at the small ends.
The connectin rod of the 5R model en ine is provided with the lubrication hole
at the ri ht side of the lar er end upper, and the piston pin bushin is lubricated
throu h this hole by pressure dischar e.
Also, the lubrication hole is drilled within the connectin rod from the lar e end
to the small end on the 3R-B and 3R-C model en ines.
The crankshaft is of carbon steel, and the bearin journals are induction hard
ened .
The crankshaft main bearin s and the connectin rod bearin s are of micro pre
cision type, and are composed of tri-metal; lead overlay, kelmet seam, and
steel back plate for smoothness and durability.
