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chamber and extending to the cylinder bores. Figure
8.
FIGURE 8
This machining change necessitated changing
the position of the piston ring locating pin for the
upper piston rings from 44° from a center line
through the piston pin to 20° from the same center
line to facilitate installation of the piston assembly.
NOTE: The old piston with the part No. 300052
cast on the inside of the piston cannot be used
with the above cylinder block.
The new piston has the number 302562 cast on the
inside of the piston near the piston pin boss and is the
type to be used in engines with the latest cylinder
machining. The casting No. 3 0 2 5 6 2 i s for identifica-
tion only. Pistons must not be ordered by this number.
Refer to your parts manual for correct part numbers
on the new pistons.
FITTING PISTONS - PAGE 3-25
The piston skirt is cam ground and tapered. The
480-490 Mechanical Procedure Manual, Figure 26
and paragraph 2 of Fitting pistons shows the maxi-
mum skirt diameter at "A", just below the third ring
groove at right angles to the piston pin. This is in
error. Correction as follows: the maximum skirt
diameter is below the fourth ring groove at the
extreme bottom of the piston at right angles to the
piston pin.
When checking piston clearance use a 1/2" feeler
gauge that will extend the length of the bore. (Use a
.002" feeler gauge for 6 cylinder engines and a
.0015" feeler gauge for 8 cylinder).
Place the feeler gauge directly opposite the piston
skirt slot when checking piston clearance.
Insert the piston with a suitable pair of piston
tongs or with connecting rod fitted to t h e piston and
with feeler gauge in position (.002" - 6 cylinder,
.0015" - 8 cylinder), the feeler gauge should be
movable under a 3 to 4 pound pull.
NOTE: Make this pull test at several points in
the bore to determine that excessive taper does
not exist. Piston pins should be a hand push fit
when piston is heated to 200° F. DO NOT DRIVE
OR HAMMER piston pins as this will distort the
piston requiring rechecking piston clearances.
CONNECTING RODS - PAGE 3-28
(6 CYLINDER)
Additional information on 6 cylinder connecting rods as
follows: Starting with car serial No. 482-108180 the pro-
cess of rifle boring the connecting rods part 300044 for the
6 cylinder engine has been discontinued and superseded
by a non-drilled rod, part no. 302293 which provides for
piston pin lubrication through a drilled hole at the top of
the connecting rod. Figure 9.
FIGURE 9
9
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