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techtalk:evo:engmech04c [2019/06/14 20:37]
hippysmack [Installing the Rocker Boxes]
techtalk:evo:engmech04c [2019/11/03 04:21] (current)
hippysmack [Compatibility]
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 So due to functionality,​ the 86-90 mid section won't fit 91-03 boxes. \\ So due to functionality,​ the 86-90 mid section won't fit 91-03 boxes. \\
 But the 91-03 middle cover will fit 86-90 boxes. \\ But the 91-03 middle cover will fit 86-90 boxes. \\
 +
 +===== Gaskets =====
 +
 +Clean the mating surfaces of all oil / trash before setting the gaskets in place. \\
 +With the bolts '​lightly'​ hand seated, check all around the box for a gasket squirting out the side before tightening the bolts. \\
 +It's easy to 'just nudge' the top section and squeeze a portion of the rubber gasket out while positioning it. \\
 +
 +{{:​techtalk:​evo:​engmech:​pinched_rocker_box_gasket_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) \\
  
 ===== Bolt Installation Sequence ===== ===== Bolt Installation Sequence =====
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 |91-03 style lower rocker box ((photo by Hippysmack))|04 and up style lower rocker box ((photo by Screw Loose Dan of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​s=c412e43a4339648eaaa7872371a84820&​p=4008995))| |91-03 style lower rocker box ((photo by Hippysmack))|04 and up style lower rocker box ((photo by Screw Loose Dan of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​s=c412e43a4339648eaaa7872371a84820&​p=4008995))|
 |{{:​techtalk:​evo:​oil:​91-03_lower_rocker_box_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​engmech:​rocker_box_screw_locations_by_screw_loose_dan.jpg?​direct&​300|}}| ​ |{{:​techtalk:​evo:​oil:​91-03_lower_rocker_box_by_hippysmack.jpg?​direct&​300|}}|{{:​techtalk:​evo:​engmech:​rocker_box_screw_locations_by_screw_loose_dan.jpg?​direct&​300|}}| ​
 +
 +===== Check Pushrod Length =====
 +A hydraulic lifter has a plunger in it's body that has about .200" of movement. ((http://​www.hammerperf.com/​ttpushrodlength.shtml)) Oil sits under the plunger and pushes it up to take the slack out of the valve train. \\
 +In the ideal world, the plunger is approximately centered in it's travel, meaning it's preloaded about .100". \\
 +So in theory,\\
 +It could move up, thus lengthening the effective length of the lifter to compensate for a pushrod that's up to .100" too short. \\
 +And likewise, it could move down, thus shortening the effective length of the lifter to compensate for a pushrod that's up to .100" too long. \\
 +This self adjusting action is also useful for compensating for changes in needed pushrod length due to engine temp variations. \\
 +As the motor heats up, the top end grows and the lifter automatically takes up the slack. \\
 +In reality, \\
 +The useful operating range of the lifter plunger is only about .050" in either direction away from centered (.050" to .150" of preload). \\
 +Outside of this range, the self adjusting function doesn'​t work nearly as well. 
 +
 +You can measure lifter pre-load to determine if the pushrods are in the size range needed. This method will get you close. ((http://​www.hammerperf.com/​ttpushrodlength.shtml)) \\
 +The cam lobes should be down (as they should be when installing a rocker box). \\
 +Set the pushrods in place (the longer one goes on the exhaust) and then place the gasket and rocker box on top installing the four big screws only. \\
 +Finger tighten the left (spark plug) side, while making sure the right side is resting with the upper pushrod ends sitting in the cups on the rocker arms. \\
 +Use a caliper to measure how much gap you have between the rocker box and the rocker box gasket. \\
 +The lifter preload should be app. .100" but anywhere between .050" and .150" should work. \\
 +Aftermarket pushrods can be purchased in longer or shorter lengths than stock ones to get the measurement within .100".
 +
 +{{:​techtalk:​evo:​engmech:​lifter_preload_by_aswracing.jpg?​direct&​200|}} ((photo by aswracing of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=322680&​page=5)) \\
  
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