Monsurin g plug gnp . gaugo ;;:;;;-;;;"",,',,"," ignition sysICm spccilicalions) should have a sliUht 'drag' when slid between the olocuuch~s. Adjust {[liP if necessary
N orm al. r, dcpo~il~.liUlolly coaled corc nose. increasing by around 0.00 1 in (0.025 mm) pc, 1000 miles (1600 km). Plugs ideally suited to en\j ine. "nd engine in good
condition
Oil fouting. Wet. oily dr~pOl;its. cal,se eventually misfirc. Fllult : wmn bores/ilision 'ingSOf valve guidcs: sometimes OCC"'!! (temj.lO'Hrilyl d .. ring lunning-in
poriOd. Plug~ C()I1 IJ() H! u~ecl "ftc. thorouUh cleaning
-," ..
. \\'
in Electrode demoge. ;;;;,:;;;;;;;:;;;~;~;';::;;i ;;,,, ",,;; h;,
bumed, glazed appearance. Fa ult: pre')gnohon Check: as 101 'Overheating' bllt may be more sovero. Discard plugs ar1d rornedy fault belorc piston or v31vc d~",age occurs
.'
.. ", . ~,'''':c." ~~:~~~~~~::i, Adjusting plug gap. Tlu, plug gap is, 03rth electrode inwards, or oulwards, as I correct clearance is uillaim!d. NOlO II,,! use 01 tho COlfcct tool
spark ami I I' Chock: cMhulOllor , • sellings, 1I0al level ,lIld iot siles; c hoke (lJlOla lion .mel cltlanli n()ss 01 ai, fillel. Plugs can bo rcusod
vlJlue, iunitiun limill H. I"clu t;lillle I1Itillu (tOO lowl
i Split cor o noso (mny npllollI i 8 crBck). Damage is
sel f.evide nt, bUI cruc ks will only showalter cloaning. Faul t: preignition 01 wrOIl!) !)ap settin!) technique. Check : ignition liming,
cooling SYStCIl1. 1",,1 O C t;"" .. r alin!) (too low) and fuel mixlure lton woak) . Discilld "Iu!)s. ",Clllv laul t immediately
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,6 Chapter 4 Ignition system
9 The spark plug gaf} is 01 conside rable impor1~e. as. if it is too lilrge or too small. the size of the spark ilnd its efficiency will be seriously impilired. The spilrk plug should be set to the ligure given in thl} Specifications ill the beginning of this Chapter; IOTa sel it, measure the gilp with a/cere, gauge. and then bend open. or close. the outer plug electrode untillhe correct gap is achieved. The centre electrode should never be benl as this may crack the insulation ilnd cause plug fAilure if nothing worse. 11 Relit the plugs, and re/ilthe leads from the distr ibu tor in the correct I"ing order. which is given in the Specifications. Screw the plugs in by hilnd initiilily then tighten them to the specified torque using the plug spilnnel.
12 Fault diagnosis -ignition system
By lar (he nlo1jori (y 01 brCJkdown and running troubles ilre caused by InUits In the igrlOlron system er(her in (he low (enSlon or high tens ion circuns There
Engine fails 10 staft 1 If the engine falls to StM( and t he cal was IIJnning norll1t1l1y when.t wns IJst used, first check ther e is fuel in the petrol wnk. If (he engille tums ovel normally on (he starter 1I10tor and the bilHery is evidently well chmged. then the lault mny be in either the high or low tension circuits. Firs( check Ihe HT circuit. Note: If lire hal/cry is known 10 hI! {(Illy ch,}lged, Ihe ignilion liglll cOllies on, ,1I)d Ihe s/arler 1II010r {,lils /() tum IIIe ongine check the tightness o f the le'lds on the biltlely terillinilis ,1I)d <1Iso (lte seCUIIHWSS oflhe e,l,th leold (0 irs cOllllec/ion 10 tire body It is qui(e common for tlie le,1(ls /0 Ii,}ve wOlked loose. l.'vc'1I If Ihey look ,1n(/ lecl seclI,e. /I one 01 the boll/my ((:{minM {Josts [11.'1.1' vC'IV liot wi".." (Iyiny (0 wOlk Ihe s/mler 1II0tOl (his is ;/ sUie IIId'C,7/IUI/ 0/ ;/ I;wlty COllllel;('On 1(1 1h.11Ie"lIillal. 2 One of tile commonest rOilsons lor bad stmtln!J IS wet or d;UllP sp,uk plug lead~ and dlstribu(or. Hemove (he distllblltor cap. H "JOdenSil(Ion is v iSIble IIlte!llillly dry the CJp With il rag and also wIpe ;lCf the leads nelu the cap_ 3 If (he enUiue sull fmls 1 0 St.l.t. check that cunent IS reachlllg (he JUS, by dlscounectln!1 ench plug le,l<1 in turn ilt the sp1Hk plllU end, .. ,ld holdlllg Ihe end olthe callie about 5 mm (0.2 Ill) aWilY from the cylillder block. Spin the enu'ne all the sta rter motor. 1 Spa,klllg between the end of the cable ilnd Ihe block should he fa"ly strong With J strong leuulm blue spark_ (Hold (he lead WI(h wbber to ilvold elec(IIc shocks) If Clluelll is reilching (he plugs. then rel110Ve them and clean and reg,lp them. Tho engine should now SWrt 5 If there is no spilrk ilt the plug leilds. wke of! the HT lead from the cenlre of the d'sltibutor C
Engine misfires 10 If the enOlnr. mlsfues re!Julariy. run It ilt a f~st irllrng speed. Pull off eilch 01 the plu(! C,lpS III hUll nnd hsten t o (he note 01 the engrne. Hold the phl(J cnp In il dry cloth or with a rubber g love
(,J) The cOllm.lV be {,lufly giving ,111 iniNmil/elll mislile (b) Thele limy he ,1 (/iJmiJged wile or loose cOrlflee/ioll in till! low (eflsion circuil (c) The condensel /II,lY I;e shOll circuiling (i{ filled) (d) There nwy be a meehanic,lllolUI! IiI Ihe dis/flbll/or (bfOken dliving spindle or eOlllac/bleaker spring. if filled)
17 If the ignition (iming is too far reto1lded, it should be noted thallhe engine will tend to overheat. and there will he a quite no(iceable drop in powel. If the engine is overheating and Ihe power is down, and Ihe ,oni(ion tim in!) is correct. then Ihe carburenor or fuel injection should be checked, i1S ,I is likely that this is where the Iilult lies.
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