Mercury MerCruiser MCM 454 Mag MPI Service Manual page 287

SERVICE MANUAL NUMBER 23
4. Check cylinder head gasket surfaces for warpage with a machinist's straight-edge and
CYLINDER CONDITIONING
1. Performance of the following operation depends upon engine condition at time of repair.
2. If cylinder block inspection indicates that block is suitable for continued use (except for
3. If cylinders have less than .005 in. (0.127 mm) taper or wear, they can be conditioned
4. When pistons are being fitted and honing is not necessary, cylinder bores may be
CYLINDER BORING
1. Before using any type boring bar, file off top of cylinder block to remove dirt or burrs. This
2. Measure piston to be fitted with a micrometer, measuring at center of piston skirt and
NOTE: Hone cylinders as outlined under "Cylinder Honing" and "Piston Selection," follow-
ing.
3. Carefully observe instructions furnished by manufacturer of equipment being used.
CYLINDER HONING
1. Follow hone manufacturer's recommendations for use of hone and cleaning and lubrica-
2. Occasionally, during the honing operation, thoroughly clean cylinder bore and check
Index
90-861326--1 MARCH 1999
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a feeler gauge, as shown. Take measurements diagonally across surfaces (both ways)
and straight down center. If surfaces are warped more than .003 in. (0.07 mm) in a 6 in.
area or .007 in. (0.17 mm) overall, block must be resurfaced by an automotive machine
shop.
a - Machinist's Straight Edge
b - Feeler Gauge
out-of-round or tapered cylinders), they can be conditioned by honing or boring.
with a hone and fitted with high limit standard size piston. A cylinder bore of more than
.005 in. wear or taper may not clean up entirely when fitted to a high limit piston. To
entirely clean up the bore, it will be necessary to bore for an oversize piston. If more than
.005 in. taper or wear, bore and hone to smallest oversize that will permit complete
resurfacing of all cylinders.
cleaned with a hot water and detergent wash. After cleaning, swab cylinder bores
several times with light engine oil and a clean cloth, then wipe with a clean dry cloth.
is very important to prevent boring bar tilt, with result that bored cylinder wall is not at
right angles to crankshaft.
at right angles to piston pin. Bore cylinder to same diameter as piston and hone to give
specified clearance.
tion during honing.
piston for correct fit in cylinder.
454 CID (7.4L) / 502 CID (8.2L)
a
b
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