Chevrolet 1988 Light Duty Truck Repair Manual page 367

Figure 22— Checking the Block Gasket Surface
must be flat within 0.10 mm (0.004-inch) to assure
that the gasket will provide a tight seal between the
cylinder head and the block.
CYLINDER BORES
For inform ation regarding cylinder bore measuring and
r e c o n d itio n in g , re fe r
MECHANICAL (SEC. 6A).
PISTON AND CONNECTING ROD
ASSEMBLIES
For inform ation regarding disassembly, cleaning and
inspection and assembly of piston and connecting rod
assemblies, refer to GENERAL ENGINE MECHANICAL
(SEC. 6A).
For p isto n s e le c tio n in fo rm a tio n , refer to " P iston
S election" in this section.
PISTON SELECTION
In order to select the proper piston for each bore, it is
necessary to measure the outside diam eter of the piston
and the inside diameter of the bore. Once the diameters
have been measured, the difference between the bore
diam eter and the piston diam eter will be the piston to bore
clearance.
1. Check the used piston to cylinder bore clearance.
M easu re (F ig u res 23 and 24)
C ylinder bore diam eter using a telescoping
bore gage. Measure the bore parallel to the
crankshaft at the gaging point which is 57.15
mm (2.25-inch) from the top of the cylinder
bore. By m easuring at this point, the smallest
bore diameter will be obtained.
Piston diam eter with a micrometer. Measure
the piston skirt at a right angle to the piston
pin, at the centerline of the piston pin, which is
to G E N E R A L E N G IN E
2.5 LITER L4 ENGINE 6A1-15
B ore G a g in g P o in t
P is to n G a g in g P o in t
Figure 23 — Measuring the Piston Diam eter
46.037 mm (1 13/ie-inch) from the piston crown.
By m easuring at this point, the largest piston
diam eter will be obtained.
• Subtract the piston diam eter from the cylinder
bore diam eter to determ ine the piston to bore
clearance.
• Refer to " S pecifications" at the end of this
section to determ ine if the piston clearance is
in the acceptable range.
If the used piston is not acceptable, determ ine if a
new piston can fit the cylinder bore.
3. If a new piston does not bring the clearance within
tolerances, the cylinder bore must be reconditioned.
Mark the piston to identify the cylinder for which it
was fitted.
1 1 3/l 6
-Inch
F-01996