Chevrolet CAMARO 1979 Service Manual page 525

Even Fire V.6 647.19
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of the cylinder, remov€ by scraping or sanding.
2. wipe bores and pistons clean, removing oil or other
foreign materiâI. Seleci a piston-rod assembly for the bor€
to be filted (or piston ând pin ifâ new piston is being fitted)
and position down into the bore with the topofpiston down.
See Fig. 647-37. The piston shoùld fail free by its own
weight through the bore when the bottom ofthe piston skirt
is 1/2" (l3mm) to 1" (25.4mm) from top ofblock. Se€ Fig.
6A7-38. Caution musi be used to insurc piston is not
damaged when it "falls" through rhe cylinder. lfit doesn't,
the piston fit is too tight ând ânother piston should be
selected until the piston will siide freely through the bore
without âny force being applied. Mark piston and bore for
3. After â pisron has been selected, which will slide
freely through a bore, it Inust be determined ifpiston fit will
be too loose. This is done by plâcing a .0025" (.06mm) feeler
gage for used pistons, and a.002" (.05mm) feeler gage for
new pistons ai least 6" (152mm) loldg ^ d not oler l/2'
(l3mm) wide, down inio th€ same bore with selected piston
v/hile holding feeler to top of the bore. See Fig. 6A7-39.
Fig. 6A7-41-coiiecr
y Fined Used Pisron
Position selected piston and feeler down into the bore
until the bottom of the skirt is a9ain 1/2" (13mm) to 1"
(25.4mm) fron top ofblock, being sùre that lhe fèeler gage
is 90' from the pin. If the piston hângs on the feeler gage
ând does not fall free, it indicâtes that lhe piston is corectly
fifted 1o that r€spective bore. See Fig. 6A7'40 and 647-41.
Mark both piston and bore b€fore going to the next bore.
If the piston fell free during this check with the .0025"
(.06mm) feeler gage [.002" (.05lnm) feeler sâse for new
pistonsl then that particulâr piston is too smali for the bore
and â larger diârnerer picron $ill be requirec.
NOTICE: when checking nore than one bore, it is
very possible thât what may be a pision too small for
one bore will be a correct fit in anolher. It is very
improbable thât any engine will require all 6 pistons
to be changed.
FIÎTING NEW PISTON RINGS
When new pislon rings are install€d without reboring
cylinders, the glazed cylind€r walls should be slighlly
dull€d, but without increâsing the bore diâm€ter, by means
of the finest grâde of stones in a cylinder hone.
New piston rings musl be checked for clearânc€ in
piston grooves ând for gap in cylinder bores The cylinder
bores ând piston grcoves must be clean, dry and free of
with
ngs instâlled, check cleârânce in grooves by
ins€rting feeler gages between each ring and its lower lând
becâuse any wear that occurs forms â step at inner portion
If the piston groov€s have worn to the ext€nt that
relatively high steps exist on the lower lands, the piston
should be replaced becâuse the steps will interfere with the
operation of new ûngs and the ring clearances wili be
excessive. Piston rings are not fumished in oversize widths
to compensate for ring groove wear.
when fitting new rings to new pistons the side
clearânce oflhe compression rings should be .003" to .005"
ând side cleârânce ofthe oil.ing should nol exceed .0035".
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