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techtalk:ref:engmech01h [2018/09/19 03:18]
hippysmack [Test Fitting Cams]
techtalk:ref:engmech01h [2019/08/16 14:01] (current)
hippysmack [Lifters]
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 ====== REF: Engine Mechanicals - Sub-01H ====== ====== REF: Engine Mechanicals - Sub-01H ======
-====== Test Fitting Cams ======+====== ​Clearancing for and Test Fitting Cams ====== 
 + 
 +====== Clearancing ====== 
 +==== Cam Lobes ==== 
 + 
 +|The underside of the lifter bosses often need a little \\ grinding to keep the cam lobes from contacting. ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=668404#​post668404))|Big cam lobes also may try to hit the pinion race, \\ which protrudes from the case slightly. It sticks out \\ farther on 2000-up motors. ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=668404#​post668404))|If the lobe is contacting the pinion race, it's better to \\ modify the lobe than the race (this is a Red Shift 567). \\ Notice the chamfer on the lobe below. Modifying that \\ race is difficult and risky. People have done it and \\ trashed the bearing in the process. ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=668404#​post668404))| 
 +|{{:​techtalk:​ref:​engmech:​clearancing_the_engine_for_bigger_cams_1_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​clearancing_the_engine_for_bigger_cams_2_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​ref:​engmech:​clearancing_the_engine_for_bigger_cams_3_by_aswracing.jpg?​direct&​300|}}| 
 + 
 +==== Lifters ==== 
 +See also [[techtalk:​evo:​engmech02b|91-99 Lifter Pin Upgrade to 00-05 Lifter Pin Screws]] in the Sportsterpedia. \\ 
 + 
 +Another thing to check is tappet pin clearance. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=668404#​post668404)) \\ 
 +The tappet pin rests against the flat on the tappet to keep the tappet from rotating in the bore. \\ 
 +But a bigger cam lobe lifts the tappet farther and on stock lifter, it can run out of travel. \\ 
 +Aftermarket lifters as shown below sometimes have longer flats. \\ 
 + 
 +|Stock vs Jims lifter tappet flat comparison. ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=668404#​post668404))| 
 +|{{:​techtalk:​ref:​engmech:​tappet_pin_comparison_2_by_aswracing.jpg?​direct&​300|}}| 
 + 
 +Small base circle cams can help with all these clearances. \\ 
 +It's because they achieve their extra lift, at least in part, by letting the lifter down farther as opposed to raising the lifter more. \\ 
 +The 575's are small base circle so it makes them simpler to install. \\ 
 +But small base circle cams often introduce one other problem and that's the clearance between the bottom of the tappet and the top of the cam bushing. \\ 
 +When the lobe sets the tappet down, the roller needs to keep following the lobe. \\ 
 +But sometimes with a small base circle cam the lifter will hit the cam bushing and thus not come all the way down. \\ 
 +Easy to fix with some careful, slight grinding on the tappet on the underside of the axle support boss. \\ 
 + 
 +==== Rocker Box ==== 
 +See more on [[techtalk:​evo:​engmech04b#​rocker_box_rocker_arm_inspection_and_servicing|Clearancing and inspecting the Rocker Boxes]] in the Sportsterpedia. \\ 
 + 
 +Check the clearance between the rocker arm and the underside of the rocker box cover. ((http://​www.hammerperf.com/​ttinstallkit.shtml#​ClearanceBoxes)) \\ 
 +With high lift cams, the rocker arm will often make contact with the rocker box top. \\ 
 +You can use a little play-dough or modeling clay to check this clearance. \\ 
 +Place it in the areas as in the pic below, install it and turn the engine over. \\ 
 +Then remove the cover and see if anything got up intp the clay and where. \\ 
 + 
 +Pull the tops and look for little marks on the inside. ((HAMMERSALES of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1120605)) \\ 
 +There shouldn'​t be any outside of factory casting marks. \\ 
 +Rocker or pushrod contact will appear as marks that shouldn'​t be there. \\ 
 +If any are found, a little strategically located grinding cleans it right up. \\ 
 + 
 +Occasionally,​ 536 cams can cause the rocker arms to hit the rocker box tops (on the pushrod side). \\ 
 +This is rare, but it can happen. \\ 
 +Contact here should cause any damage, but it'll cause noise and leaks. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5489961)) \\ 
 +A lot of rocker box top leaks have been traced to this. 
 + 
 +The most critical clearance in the rocker box is the clearance between the valve springs and all areas of the rocker box around it. ((http://​www.hammerperf.com/​ttinstallkit.shtml#​ClearanceBoxes)) \\ 
 +If the valve spring or retainer is allowed to touch the rocker box, it forces the valve to land sideways on the seat. \\ 
 + 
 +|  Rocker box top damage ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=5489961)) ​ |  Lower rocker damage from valve spring impact ((photo by ReddTigger of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=4593655)) ​ | 
 +|{{:​techtalk:​evo:​engmech:​rocker_box_clearance_3_by_aswracing.jpg?​direct&​300|}}|{{:​techtalk:​evo:​engmech:​rocker_box_damage_3_by_reddtigger.jpg?​direct&​300|}}| 
 + 
 +==== Rocker Arm Contact ==== 
 +This condition was noticed when using S&S roller rocker arms and big cams.  
 +But these areas can be checked while using stock or other rocker arms also.  
 +Symptoms were a ticking noise on the top end on cold starts. 32)  
 +The roller rockers were just grazing the rocker box assembly.  
 +All 4 were just barely nicking the box.  
 +It stopped when the bike got warm and stretched.  
 +Clearance can be done with a die grinder or Dremil Tool.  
 + 
 +|You can see where the contact occurs. ((photos by madnss of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1776474&​highlight=rocker+arm+bushings))|| 
 +|{{:​techtalk:​evo:​engmech:​rocker_box_clearance_1_by_madnss.jpg?​direct&​200|}}|{{:​techtalk:​evo:​engmech:​rocker_box_clearance_2_by_madnss.jpg?​direct&​200|}}| 
 +\\ 
 + 
 +**Here are some useful cam installation links**: \\ 
 +From Hammer Performance:​ [[http://​www.hammerperf.com/​ttxlcaminstall.shtml]] \\ 
 +From NRHS: [[http://​www.nrhsperformance.com/​tech_xlcaminstall.shtml]] \\ 
 +====== Test Fitting ​======
 Factory fitting of the cams is (or rather was) all about noise control. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1840595)) \\  Factory fitting of the cams is (or rather was) all about noise control. ((aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1840595)) \\ 
 By selecting the cam gears sized specifically for the engine they were going in, they could walk that fine line between noisy and too-tight. \\ By selecting the cam gears sized specifically for the engine they were going in, they could walk that fine line between noisy and too-tight. \\