Camshaft Degreeing Procedure 1
Intake Centerline Method There are several accepted ways to degree a camshaft. COMP Cams® suggests the intake centerline method as the easiest and most accurate. This method of cam degreeing is very practical and indifferent to design characteristics. It simply involves positioning the center, or point of maimum lift, of the !" intake lo#e with Top Top $ead Center of the ! !" " piston. The intake centerline method still re%uires accuracy to #e correct, #ut it is somewhat forgiving. Once you have degreed a camshaft using this method, you will #e surprised at its ease. &e also recommend positioning the dial indicator on the !" intake retainer #ecause lift measurements will include any deflection that may occur in the pushrod ' and rocker arm. This makes the degreeing process as accurate as possi#le in relation to what actually goes on inside the engine. (tep ") The camshaft and timing set have #een installed. Make sure that the timing marks on #oth the cam gear and crank gear are aligned properly per the cam installation instructions. *se chalk or similar marker to #etter define the marks. (tep +) or eample, we have our cam card and it suggests we install the cam on "- degree intake centerline. Install all the rocker arms and pushrods in the eng ine as normal. On !" intake lo#e, install the solid lifter in place of a hydraulic lifter. If a solid lifter or roller cam is #eing checked, use that respective lifter. /d0ust the !" intake lash to eactly 1ero. $o not pre2load the lifter. 3et, ad0ust the !" ehaust lash to 1ero. 4ou 4ou should #e a#le to turn #oth pushrods with your fingers easily. (tep 5) /ttach the pointer to the #lock. Many people will make a pointer out of some sort of rigid, yet managea#le wire. / stiff stiff coat hanger wire works well. (tep 6) /ttach the degree wheel to the #alancer and install the assem#ly on the crankshaft. There are several ways to attach the degree wheel to the crankshaft. The crank may #e rotated from either the front or from the flywheel end. O#viously, if the engine is in the car, you must rotate from the front. 7emem#er, the greater the leverage, the smoother the crank rotation, thus more accuracy. 3ote) 3ever use the starter to turn the engine while degreeing a cam. (tep 8) 9efore installing the piston stop, rotate the crankshaft to get the !" piston in approimate T$C position with #oth the intake and ehaust eh aust valves closed. This can #e a rough guess, #ut it can save you from making a mistake later. /d0ust /d0ust you pointer to 1ero or T$C on the degree wheel. (tep ) Turn the crankshaft opposite the engine rotation approimately "82+- degrees. This will lower the position enough to allow the T$C stop to #e installed in the spark plug hole. (crew in the piston piston stop until it touches the piston. Continue to turn the engine in the same direction until the piston comes #ack up and touches the piston stop. Mark the degree wheel with a pen or pencil on the num#er the pointer is on. Turn the engine in the other direction, same as engine rotation, until the piston comes #ack up and touches the piston stop. Make a mark on the num#er the pointer is on. (tep :) 7emove the piston stop after marking th e two points on you degree wheel. 7otate the crankshaft to the midpoint of the two marks. This point is T$C for cylinder !". &ithout rotating the crankshaft, ad0ust the degree wheel to read - degrees at the pointer. 4ou 4ou are now ready to locate the intake lo#e centerline relative to T$C. If
you are not a#solutely sure that your - degree mark is set at T$C, repeat this procedure. This step #y step is critical to proper cam alignment. (tep ;) /ttach the dial indicator to the dial indicator mount. Position the dial indicator mount so the tip will contact the retainer of the intake valve. It is important that the indicator plunger #e p arallel to the valve stem. /ny variance in the angle of the indicator will introduce geometric errors into the lift readings. (tep ') 7otate the engine in the normal direction of rotation until you reach maimum lift. The dial indicator will change direction at the point of maimum lift. /t this point, set the dial to 1ero. "(tep "-) 9ack the engine up 3et, turn the engine forward in the normal direction of rotation until the dial indicator reads .-8-> #efore maimum lift. 7ecord the degree wheel reading. (tep "") Continue to rotate the engine over in its normal direction of rotation until the indicator goes past 1ero to .-8-> on the closing side of maimum lift. /gain, record the degree wheel reading. (tep "+) /dd the + num#ers together and dived #y +. That num#er will #e the location of maimum lift of the intake lo#e in relation to the crank and piston. This is the intake centerline. or ea mple) The first degree wheel reading was ' degrees. The second reading was "" degrees. These two num#ers <' ? ""= added together will #e +"+. +"+ divided #y + will e%ual "-. 4our actual intake centerline is "- degrees. 7eference #ack to your cam spec card and see what the recommended intake centerline is. In the event that your camshaft did not degree in as per manufacturers@ specs, it will #e necessary to either advance This video covers all of the points discussed here and illustrates many other helpful tips to achieve the maimum performance from your engine. If you wish to order this video, or if you have any other %uestions concerning your cam change, please call our C/M DEP® line at "2 ;--2'''2-;85. Our technical specialists are her to help you : /M to ; PM
Common Mistakes 3ote) To prevent #roken or damaged valve train components, please read and follow these instructions completely. F Then num#er one cause of mechanical and hydraulic camshaft failure is worn or inco rrect valve springs which results in premature wear of camshaft lo#es and lifters "" F COMP Cams® strongly recommends replacing valve springs on any engine with -,--- miles or more. (tock
Procedure + How t odegr eec ams. Us eapenc i l ,paperandar i t hmet i cf ort hi spr oc edur e,t ok eept r ac koft her es ul t s . Fas hi onar i gi dpoi nt erf r om s t i ffwi r eoranol dc oathangerandat t ac hi tt ot heengi nebl oc k.Thi spoi nt erl oc at es t h ed eg r e eso nt h ed eg r e ewh ee l . Wi t hade gr eewh eel i ns t al l e dont hec r a nk s haf t ,r ot at et hec r ankt og ett h eno1-pi s t onatTDCan dc hec kt o ens ur et h att h ev al v esar ef ul l yc l os edt h enadj us tt hep oi nt ert oz er o( 0 ºTDC)ont h edegr eewhe el . T ur nt hec r ank s haf toppos i t et her unni ngr ot at i onappr o xi mat el y1520degr ees .I ns t al l api s t ons t opont het opof t hee ngi nebl oc kf as t en edi npl ac eb yt woheadbol t sori nt h ec as eofo v er headc amsi ns t al l t hepi s t o ns t opi nt o t h es p ar kpl u gh ol es .No t e :Ad i a lg au gec a na l s ob eu se d. Cont i nu et ot ur nt h ee ngi nei nt hes amedi r ec t i onu nt i l t h epi s t onc omesbac kupandj us tt ouc hest hepi s t ons t op. Ma k eano t eoft h ee x ac tn umb ero nt h ed eg r e ewh eel t ha tt h ep oi n t eri so n. Rot at et heengi nei nt heot herdi r ec t i on( r unni ngr ot at i on)unt i l t hepi s t onc omesbac kupandt ouc hest hepi s t on s t o p.Ag ai nno t et h en umb erwh er et h ep oi nt e ri s . Remo vet hepi s t ons t opandr ot at et hec r ank s haf tt ot hemi dpoi ntoft het womar k s .Att hi spoi ntt hepi s t oni satt he t r uet opdeadc ent er .Loos ent hedegr eewheel andadj us ti ts oi twi l l r ead0ºTDCatt hepoi nt er .Don' tr ot at et he c r a nk shaf tt odot hi s ! Now,i t ' st i met ol oc at et hel obec ent er l i ner el at i v et oTDC.At t ac hadi al i ndi c at oront het opoft heengi nebl oc k. Sett het i pt oc ont ac tt het opoft heno1c y l i nderi nl etv al v es hi m/ buc k et .Chec kt omak es ur et hatt hei ndi c at or pl ungeri spar al l el t ot hev al v es t em.NOTE-anyvar i anc ei nanangl ewi l l pr oduc egeomet r i cer r or si nt hel i f t r ea di ngs . Rot at et heengi nei nt henor mal di r ec t i onofr ot at i onunt i l ar eadi ngont hedi al gaugeof0. 040?l i f ti sr eac hed. ( Va l v ewi l l s t a r t t oo pe n)Mar kt h ed i a lg au gean dma k ean ot eo ft h er e ad i n go nt hed eg r e ewhe el . Cont i nuet ot ur nt heengi nei nt henor mal di r ec t i onpas tmax i mum l i f t .Thev al v ewi l l nowr et ur nt oi t scl os e pos i t i on.Mak eanot eoft hedegr eewheel r eadi ngwh ent hei n di c at orr eads0. 0 40"ont her e t ur ns i de No wa ddt h el a r g ero ft h et wor e ad i n gst h aty o un ot e do nt h ed eg r e ewh ee lt o18 0s ub t r a ctt h es mal l e rn umb er andt hendi v i det hean swerb yt wo .Yourans werwi l l i ndi c at et hel obecent ero ft hecam.Ex ampl e:openr eadi ng wa s4a ndc l o s er e ad i n gwa s43 .No wa dd43t o18 0=2 23 ,s u bt r a c t4=2 19di v i d eb y2=1 09 . 5 .L ob ec e nt e ri s 1 09 . 5d eg r e es . Co nt i nu et omo v et h ec am o nt h ead j u st a bl ec am g ea ra n dr e dos t e ps10t o1 2u nt i l t h er e qu i r e dl o bec e nt e ri s a c hi e v e d. No wd ot h es a mef o rt h ee x h a us tc a m • • •
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Dample) Take the two recorded values (open number and closed number), add them together, and add 180. The result is the cam's duration at 0.050inch li!t. "ivide that !igure b# two. $e%t, subtract the opening value recorded at 0.050inch o! li!t !rom this !igure. The result is the current centerline. &or e%ample * (open +T") - 5* (close +") -180* (distance !rom T" to +") / 5* (total duration at 0.050 inch li!t) / 18* 18* * / 10* centerline Note: This
!ormula applies onl# to engines with intake valves that open +T". 2ome engines !eature low overlap cams with intake valves that open T". To set #our cam to #our manu!acturer's recommended centerline, note the di!!erence between #our current centerline and the manu!acturer's centerline and ad3ust the cam appropriatel#. 4oosen the
ad3ustable cam gear bolts and rotate the cam in the appropriate direction to achieve the correct amount o! advance or retard. &or e%ample, i! #ou've recorded a 10degree centerline on a cam that's supposed to have a 8degree centerline, it's clear that there's a si%degree di!!erence. 2ince an engine's cams spin at hal! the speed o! the crank, the cam must be advanced three degrees, not si%. 6! #ou've recorded a degree centerline, the cam should be retarded one degree, which is e7ual to two degrees o! cranksha!t rotation.
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