Weifang 495 - Mounting Cylinder Head Onto Cylinder Block; Adjusting Decompressors Travel

;The valve seat must be renew!=d jf t11e level of the valve head
IS lovler than tllat of the cylinder head bOttC)!11 stlrface by more
than: 3. 5 mm after the valve seat being reconditior·ed. Before a >new
. \~alve seat is pressed iIlto the c:vlinder }1ead ,a illterference ofO. 086
-0. 15() m.m in diameter shollld. be kept, al1d the cylinder head
~h().uldbe Ileat((d" integrally" to abollt 2()O°C.
After.pressing t.he valve seat in. ,reall] its contact·band again
accurately to ensur~ the v81~.;e seat being concentric \viththe .valve
guide ,·and meanwhile ,measure the dista11·ce frorll the cylinder head
botto·ro· surface dovvn ~() the va.lve }1eaci vvrlich slloulcl be within 1. 2
-1. 6() mrn. If it is tC)O small, the accident of valve impactil1g piston
may- OCC1Jr.
f ,.~ If ~ r-' 1· 1 T ..J...l l' d T) 1 ~
\. 4) l\:.lOlln tln.g \-jY 1111Qer t"l.eaL1 ();lto c~/ l1rl er [)-oc k
.. > 1 1. ri 1 . 1 '11 " 1 t
Before IT1ouI1tlng toe CY.tll1uer '1ead, c ·lec~~· the t"atnes.s Do&. its
bottom surfa.ce first. TJ-!e allowat~le clev'iation (jf the flatness is
vlithin o. 05 nlrll. I,f'it'is greater tha!l o. 25 rnrn (in longitudinal di-
rection) , the bottora s~urface sh9u1d be reconditi()rled by means of
scrar . r1g~ WheYl m6u:nting the cylinder heac1 ()[ltO the cylinder
block, tr1e nuts sholild be tightened according to the seqllence
sho\vn in the fig. 3.· Tighten them gradually and evenly in several
times w~ith a torque .wrench until tIle specified torque lilnit of 12-
14 Kg - nl is reached; otl1erwise; the cylinder l1ea.d may be de-
formed, tl1e cylindel· head ga.sket maybe burnt out anc! even the
cylinder liner may, b.ebroken and"some other irnportarlt parts may
be darnaged ..
(S)Adjusting Decompressor's Travel
T'urn the flywheel tl1 lift tIle pis tOll of ttle first cylinder up to
the top dead cerltre in its· comr'ressioll stroke, while the intake
valves 'on the first ane! second cylinder are closed., Turn the
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