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LP Engine G430 (3.0L)
Base Engine Service Procedure
Cylinder Boring and Honing
Boring Procedure
1. Before you start the honing or reboring process,
measure all new pistons with the micrometer,
contacting at points exactly 90° from the piston pin
centerline. Refer to Piston Selection. Select the
smallest piston for the piston fitting. Slightly varied
pistons in a set may provide correction, in case the
first piston is too loosely fitted.
2. Before you use any type of boring bar, file the top of
the cylinder block in order to remove any dirt or
burrs. If you do not check the cylinder block, the
boring bar may be tilted, this could result in the
rebored cylinder wall being at incorrect right angles
from the crankshaft.
3. Carefully follow the instructions furnished by the
manufacturer regarding the use of the equipment.
4. When you rebore cylinders, make sure all
crankshaft bearing caps are in place. Tighten the
bearing caps to the proper torque in order to avoid
distortion of the bores in the final assembly. The
crankshaft must be clear of the boring cutter when
you bore each cylinder. Cover or tape the
crankshaft bearings and other internal parts to
protect during or honing process.
Honing Procedure
1. When honing the cylinders, follow the
manufacturer’s recommendations for use, cleaning
and lubrication. Use only clean, sharp stones of the
proper grade for the amount of material you remove.
Dull, dirty stones cut unevenly and generate
excessive heat. When using coarse or medium-
grade stones, leave sufficient metal so that all stone
marks may be removed with the fine stones you use
for finishing in order to provide for proper clearance.
2. During the honing process, thoroughly clean the
cylinder bore. Check for a correct fit of the piston
you select for the indicifual cylinder.
3. When honing to eliminate taper in the cylinder,
make full strokes of the hone in the cylinder.
Repeatedly check the measurement at the top, the
middle and the bottom of the bore.
NOTICE
Handle the pistons with care. Do not force the pistons
through the cylinder until you hone the cylinder to the
correct size. The piston can be distorted through
careless handling.
4. When finished honing a cylinder bore to fit a piston,
move the hone up and down at a sufficient speed to
obtain very fine, uniform surface finish marks in a
cross hatch pattern at 45-65 degrees.
5. The finish marks should be clean but not sharp. The
finish marks should be free from imbedded particles
and torn or folded metal.
6. By measuring the piston to be installed at the sizing
point specified and by adding the average of the
clearance specification, you can determine the
finish hone cylinder measurement. Refer to Engine
Mechanical Specifications. Measure the block and
the piston at normal room temperature.
7. True up the refinished cylinder bores to have less
than the specified out-of-round or taper. You must
final hone each bore in order to remove all stone or
cutter marks and in order to provide a smooth
surface.
8. For piston-to-bore tolerance specifications, Refer to
Engine Mechanical Specifications.
9. After final honing and before the piston is checked
for fit, clean the bores with hot water and detergent.
Scrub the bores with a stiff bristle brush and rinse
the bores thoroughly with hot water. Do not allow
any abrasive material to remain in the cylinder
bores. This abrasive material will wear the new
rings, the cylinder bores and the bearings lubricated
by the contaminated oil. After you wash the bore,
brush the dry bore clean with a power-driven fiber
brush.
10. Permanently mark the piston for the cylinder to
which the piston has been fitted.
11. Apply clean engine oil to each bore in order to
prevent rusting.
