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Genuine Chevrolet piston pins are sold in standard sizes as well as .003", .005" and .010" oversizes.
After new bushings have been placed in the piston, or you are fitting any of the above mentioned oversize pins, the bushings should be reamed with an expanding piloted type reamer, similar to the one shown in Fig. 9. This reamer pilots in one bushing while it is reaming the other.
In operation, the collet assembly of the reamer is placed in one bushing and expanded into it by turning the knurled nut. This firmly locks the collet into the bushing. The reamer is then placed
Fig. 10— Fitting Piston Pins
through the opposite bushing and collet and expanded until it begins
to cut. The scale on the end of the reamer is graduated in .00025" so
that the required amount of stock can be accurately cut from the
bushings for the size of the piston pin you are fitting. It is
good practice to only ream the bushings within .0005" of the
size desired. This can be removed on the last or final cut.
After one bushing has been reamed the size of the rest of the bushings
has been established. The collet can then be removed from the bushing
and placed in the one that has been reamed and the other bushing
reamed to size, accurately and fast.
The bushings should be reamed so that it is possible to push the
pin through the bushings, with a thumb. See Fig. 10. This is known
as a thumb push fit.
9Fitting Piston Rings
The purpose of a piston ring is to fill up the space between the
cylinder walls and the piston, so as to prevent leakage of gases
and oil.
As these gases are under considerable pressure, it is therefore
necessary that the rings not only fit snugly around the cylinder
walls, but in the grooves
Fig. 11— Piston Ring Gap
of the pistons as well, otherwise the gases and oil will work behind
the rings.
Genuine Chevrolet piston rings are furnished in standard sizes
as well as .005", .010", .015", .030" and .040" .020" oversizes.
To properly fit new piston rings, proceed as follows :
Slip the ring into the cylinder, pressing it down about half way
into the bore. See that the ring is square with the cylinder walls.
Fig. 12— Fitting Piston Ring in Groove
The gap between the ends of the ring should be from .004" to
.014". Fig. 11.
If the space between the ends of the ring is less than this, remove
ring and with a very fine file dress the edge until proper clearance
is obtained. Fit each ring separately.
