CRANKSHAFT AND CYLINDER BLOCK
ENGINE OVERHAUL <4G63-Turbo>
11D-67
BORING CYLINDERS
1. Select an oversize of the pistons to be used
based on the largest of the cylinder bores.
2. Oversize pistons are available in two oversizes:
0.50 mm and 1.00 mm. Bore each cylinder to a
size that provides the standard clearance when
combined with the selected piston. The reference
position for piston diameter measurement is as
shown in the drawing.
3. Based on the piston diameter measurement,
calculate the boring finish dimension.
• Boring finish dimension = [Piston diameter] +
[0.02 − 0.04 mm (clearance between piston and
cylinder)] − [0.02 mm (honing margin)]
CAUTION
To prevent deformation of cylinder block that
would result from the heat generated by boring,
bore the cylinders in the following sequence: No.
2 → No. 4 → No. 1 → No. 3.
4. Bore all the cylinders to the calculated boring
finish dimension.
5. Hone the bored cylinders to the final finish
dimension (piston diameter + clearance between
piston and cylinder).
6. Check the clearance between the piston and
cylinder.
Standard value: 0.02 − 0.04 mm
AK300577
AC
Thrust
direction
Piston outside
diameter
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