Degreeing A Camshaft The Easy Way.

Degreeing a Camshaft.the Easy Way.For more information, see www.cranecams.comCAUTION: READ INSTRUCTIONS CAREFULLY BEFORE STARTING PROCEDUREINTRODUCTIONIt is the exception, rather than the rule, that a cam may beout of phase, but this should be established to insure anaccurate performance baseline or point of tune.Talk to any cam grinder, engine builder, or racer and you’llfind overwhelming agreement that “degreeing-in” acamshaft is a vital step along the route to optimum engineperformance. At first that may seem strange because“degreeing-in” a cam pertains to checking the accuracy withwhich it was manufactured.EQUIPMENT NEEDEDThere are four essential pieces of equipment needed toproperly check a cam: (1) An accurate Degree Wheel for thecrankshaft. (2) A rigid pointer that can be attached firmly tothe engine and indicate points on the Degree Wheel. (3) ADial Indicator to accurately measure cam lift. (4) A Top DeadCenter Piston Stop. You will find each of these pieces ofequipment supplied in your Tune-A-Cam-Kit.Actually, by degreeing-in a camshaft, you’re insuring thatvalve opening and closing events are in accordance withspecifications, regardless of the cause. Actual valve openingand closing events are influenced not only by accuracy withwhich a cam was ground, but also timing chain stretch, keyway position in the crankshaft, crank timing sprocket, anddowel pin hole position in the cam sprocket also play amajor role.Crane Cams’ Tune-A-Cam Kit (Pt. No. 99030-1) containseverything needed to degree-in a cam: Degree wheel; pointer; dial indicator; positive piston stop; checking valvesprings; plus a unique dial indicator mounting base thatscrews into a valve cover retaining bolt hole. This allows youto degree-in the cam with the heads installed, or off theengine. The mounting base is the key to Tune-A-Cam’s easeof use, as the dial indicator is easily positioned for properalignment. Minor adjustments are all that is required foroptimal geometry between the dial indicator and thepushrod. This makes for consistent and more accurate camchecking, and pays off with improved performance.WHY DEGREE-IN YOUR CAMThe purpose of degreeing a cam is to insure that the cam isphased correctly with the crankshaft, per the cam manufacturers’ specifications. Some factors that may cause improper phasing are:Tune-A-Cam KitThe supplied Degree Wheel is a metal plate with its outercircumference divided and marked into 360 degrees. This isattached to the snout of the crankshaft, so the wheel can berotated to adjust its reading in relation to crankangle/degree. The larger the wheel diameter, the moreaccurately you can read it, since there will be a greater distance between the degree points.1. Cam or crank gears are incorrectly marked.2. Keyways are out of position on gears.3. Keyway in the crankshaft is misindexed.4. Cam dowel pin or keyway is misindexed.CRANE CAMS, INC. 530 Fentress Blvd., Daytona Beach, FL 32114www.cranecams.com Tech Line: (386) 258-6174 Fax: (386) 258-61674/001803

Turn the crankshaft to lower the piston enough in thecylinder to move the degree wheel 15-20 degrees.With the rocker arms removed, screw in the pistonstop until it contacts the piston. (Figure 2) Turn theengine in the same direction until the piston comesBEGINNING TO DEGREE YOUR CAM1. Be sure that the timing set is installed with the camand crank gear aligned properly per the manufacturer’s specifications.2. Remove the rocker arms.MOUNTING THE DEGREE WHEEL1. Attach the degree wheel (using the supplied aluminum bushings if necessary to center the degreewheel) to the crank snout or balancer. In our example, we use the crank snout. (Figure 1)2. Attach the pointer from your kit firmly to the engineblock. (Figure 1)Figure 2.back up and touches the piston stop. Make a note ofwhat degree the pointer is on the degree wheel. Turnthe engine in the opposite direction until the pistoncomes back up and touches the piston stop. Make anote of what degree the pointer is on the degreewheel. Add these two numbers together then dividethem in half. Example: Let’s say that the stop pointsare 16 in one direction and 20 in the oppositedirection. The total would be 36 degrees. This figuredivided in half would be 18 degrees. Therefore 18degrees from either of your stop points is true topdead center. Now either move the pointer to alignwith the 18 degree mark on the degree wheel, orcarefully loosen the degree wheel (without disturbingthe position of the crankshaft) and move the degreewheel to the 18 degree mark, making sure that thepiston is still against the stop. Now turn the engine inthe opposite direction until the piston comes back upand touches the stop. The pointer should be alignedwith the 18 degree mark on the other side of theTDC mark. If this is correct, then you have foundtrue top dead center. It is best to repeat this to makesure that nothing has moved. If you didn’t get 18 , asper our example, you will need to repeat the procedure until you get the same amount of degrees onboth sides of TDC. Remove your piston stop and youare ready to properly degree your cam.Figure 1.FINDING TOP DEAD CENTER (TDC)1. Rotate the crankshaft until you get number one piston in approximate TDC position. Next, adjust yourpointer to the zero TDC position on the degreewheel. (Figure 1)2. It is essential at this point that you have some meansof rotating the crank that will not interfere with thedegree wheel. The crank can be rotated from eitherthe front or the flywheel end. The greater the leverage, the smoother you can rotate the crank for timing checks. (Do not use the starter for turning theengine while degreeing).3. Now that the Degree Wheel has been set at approximate TDC, and a means for turning the crank provided, you’re ready to install and set the piston stop.4/002803

MOUNTING THE DIAL INDICATOR1. The Dial Indicator mount in this kit is designed toattach into a valve cover bolt hole. Remove anyobstructions that would hinder this mounting. We willbe checking cam timing so the rocker arms must beremoved. Be absolutely certain that you use the correct type of lifter for the camshaft that is beingdegreed. This means a flat tappet for a mechanicalor hydraulic cam (do not use a hydraulic lifter, as theplunger can move), or a mechanical roller tappet fora roller camshaft. You should also take particularcare to clean off any excessive oil, grease, or lubricant from the cam lobe that you are degreeing. Eventhe slight interference of such foreign matter canalter the readings that your dial indicator will show.Figure 4.Figure 3.2. A pushrod is needed to be used as an extension ofthe dial indicator. The indicator will center in the oilhole of the pushrod tip. (Figure 3) On engines withpushrods that don’t have oil holes i.e., FE SeriesFord and Chrysler, you will need to obtain a pushrodwith an oil hole or cup end for checking purposes oruse a dial indicator extension.CAUTION: Be sure that the indicator is supportedsolidly. Any looseness will introduce major errorsin measurement.3. With the Degree Wheel and its pointer accuratelyset, and the Dial Indicator solidly in place, rotate thecrankshaft until the cam’s base circle is under thelifter for the cam lobe being measured (usually starting with Number One intake). (Figure 4) Set the dialindicator to zero at this point. Be sure the DialIndicator is pre-loaded about .300” to insure that itwill not run out of travel while on the base circle.Rotate the crankshaft to raise and lower the lifterseveral times to verify that the dial always returns toInstall the pushrod in the intake lifter of cylinder No.1 and mount the dial indicator. It is important that theindicator plunger be aligned as closely as possiblewith the lifter being measured. Any substantial anglebetween the axis of the plunger and the lifter willintroduce geometrical errors into the lift readings.(Figure 4)4/003803

zero when the lifter is on the base circle. If it doesn’t return to zero, there are several possible causes:(1) The dial indicator may not be mounted rigidly (2)The lifter may not be contacting the base circle solidly (3) The lifter could be sticking slightly in its bore.Find the trouble and correct it before proceeding.metrical, with the opening side of the lobe being much moreaggressive and the closing side being more gentle. Therefore when you attempt to locate the middle (or centerline) ofthe asymmetrical lobe there is an automatic error. It couldbe as little as 2 or as much as 6 depending on the actuallobe design. Also, the centerline method does not really indicate if your camshaft was properly produced, as no confirmation of the duration occurs. Since the opening and closing at .050” lift method is not affected by the lobe design, itis more accurate to degree this way. This method will alsoverify your actual duration figures.It may be necessary to apply slight finger pressureagainst the lifter when rotating the engine. Be careful not to bump the pushrod.Any of these camshaft checks that may be performed (base circle runout, cam timing, etc.) are alsovery dependent on your cam bearings being in goodcondition and providing the proper radial clearancefor the type and size of bearing. Excessive radialclearance will distort your figures taken of tappetmovement, resulting in incorrect conclusions regarding the camshaft installation and its condition.When checking, always turn the engine in the normal direction of rotation because of possible slack in the timing chainor gear drive.DEGREEING YOUR CAMUsing the intake opening and closing at .050” cam lift,obtained from the information on your cam spec card(Figure 5, K), turn the engine in the normal direction of rotation. Watch the dial indicator. When it moves up .050”, stoprotating the engine. Record the degree wheel number thatthe pointer is on. (In our example it is 12 BTDC, Figure 6).Then continue to rotate the engine in the same direction.Watch the dial indicator, it will change direction at maximumCHECKING BASE CIRCLE RUNOUTThis is a good time to check for runout of the cam’s base circle. This is out of roundness, or wobble, during rotation. Ifthe cam lobe is concentric with the camshaft bearing journals there shouldn’t be any appreciable runout. We try tohold base circle runout to less than .001 inch for optimumcam performance and ease of setting lash. If the runout onyour cam measures more than .002” we suggest returning itto the manufacturer.If there is measurable base circle runout on your cam,adjust the dial indicator so the runout is divided equally onboth sides of zero. This will give the minimum error forchecking the cam’s timing.CAM SPECIFICATION CARDAll the information you need for checking the timing accuracy and phasing of a camshaft is provided on the specification card that you receive with your Crane cam. (Figure 5)This will include the opening and closing timing points andthe amount of lift (at the lifter) at which the timing should bechecked. (Figure 5, K)WHICH CAM DEGREEING METHOD TO USE ?There are two popular methods for degreeing a cam: (1)using the opening and closing figures at .050” tappet lift offthe base circle of the cam; (2) using the intake centerlinemethod.Figure 6.We believe that degreeing the cam using the opening andclosing at .050” lift is much more accurate. The problem withthe centerline method is it has you finding the theoreticalcenterline of the intake and/or exhaust lobe. It makes theassumption that the lobe you are checking is symmetrical,with its opening side being the exact same shape as theclosing side of the lobe. Most modern cam lobes are asym4/00lobe lift. Record the cam lobe lift. Continue to rotate theengine in the same direction until you reach .050” beforeclosing. (In our example it is 42 ABDC). (Figure 7) If you gopast either of the .050” marks, back up at least .100” androtate the engine in the normal direction again until youreach the .050” mark on the indicator.4803