DMWR-9-2815-220
AVDS-1790 ENGINE OVERHAUL STANDARD
DEPOT MAINTENANCE WORK REQUIREMENT
DMWR-9-2815-220 - Page 328 of 1422
)
±
I
DMR 9·2815±220
5-37.
(Cont)
(a)
Seat dressing±
A 45 DeGree an
²
³le stone must be UseD to GrInD the
exhaust vaLve seat, an´ a 15 deGree anGµe GrfOd¶nG stone must Be used FoR the
iNtake vaLve seats·
¸ress the seat on The
insert wIth the stone usinG a vaµve
¹seat GrindInG MachIne.
Aºter DressinG tHe seat oº tHe Insert, inspect vaµve con»
T¼ct as DescrIbeD In ParaGrapH 5½3
?
¾ b (4)
_
5/¿58).
(b) Seat widtHÀ When 360 deGre
²
Áo
³´
ct is oBtained, narrow tHe seat on
tÂe insert to tHe wIDtH speciFIeD in FiGUre
Ã
5
½
41 (5/¿95) by GrInDinG the Inner
waµL and eXposeD Face oF tHe Insert to tHe anGµes sPecIFIedÄ
KeeP vaµve seat
area as near as possIBLe to tHe cenÅer oF tHe vaµve ºace.
Vaµves sHouµD never
seat at tHe top or bottoÆ oº tHe vaµve Face area·
(3)
VaLves.
ÇiscarD vaµves tHat have warpeD¾ cracÈeD¾ PitteDÉ or burned
Faces.
Aµso DÊscarD vaLves HavInG baDLy Pitted, scored¾ or scratcHed steMs or
ËocÈinG Grooves·
ÌeFace sµÊGhtµy pitteD or Burned vaµves tHat do not have 3Í0
deGrees oº contact to LiÆIts sPeciÎIeD in FiGure 5½41 (5/Ï95)À
¸IscarD vaLves
tÐat cannot be rEFaced to these LimIts·
CHecÑ vaµve µenGth From seat contact to
tiP oF steM aFter GrIndiNG¾ as sHown in ºiGure 5Ò41 (5/¿95)·
¸iscarD vaµve iF
µenGtH is not withÓn the LIÔIts sPeciFIed·
(4)
CYµinder Bore·
Cyµinder Bores sHouµd Be re
$
rounD to tHe neÕt oversIze
aÖcordinG to overs×ze standards µisted in tØBµe 5½10 Ù5/
¿53
) when bore DiÚnsions
aRE not witHIn LiÔitsÀ
AFter tHe cyµinDer bore has Been reGrounD oversIZe¾ the
cÛµInDer asseMBLy IdentiFication nuÜer (ºiG·
5Ò32) (5/157) sHouµD Be cHanGed in
aÖcordance with the part nuÔBers µIsted In T¼bµe 5Ý¿1 (5/Þ57) to reFµect tHe
reGround bore sIze·
ßhe cyLInDer asseMBLy shouLd aLso Be reGrounD oversIZe when
tÐe cyµInDer Bore is FounD to Have excessIve scratchesÉ scorinGà rinG r
á
iDGeÉ or
wÐen tHe bore Is GLaâeã or smootH.
ALµ cyµinder bores Must Be honeD aºter GrInd»
IäG and/or BeFore new pIston rinGs arE InstaLµedÀ
åyµInDer Bore honInG speciFI»
cations and recoæçendeã ProcedurEs are outµIned Beµowè
/
(a)
CyµInder Bore honinG séecIFications·
i
G
²
êross hatch anGµe to Be 35
/
Grees oFF tHe HorIâontaL·
2
Cross hatch to Be cUt uniForÔµy
ë
in Both DirectIons.
3
Cross hatch to Be cµeanÒcut¾ But not ìsHarP, and ºree From torn or
Fíµded ÔeîaµÀ
4
ïhe MicroÝFinIsh rouGHness sHoUµD averaGe Between 35 and 45 micro»
I NcHes¾ ðs (rootñmeanÝsquare DeviatIon From tHe òan)¾ as óasUreD on a Proô
FiLometerÀ
5
ïHe pLateau area sHouLD Be ¿/2 to 2/3 oF tHe surºace area.
Í
ïHe pµateau shouLd Be ºree ºroM BurnIshed or Gµazed surFacesÀ
7
ïHe surFaõö ÷ust be ºree oº eMbedded PartIcLesÄ
5/¿9Í
µ
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