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techtalk:evo:engmech04b [2021/07/13 04:08] hippysmack [Middle Rocker Box Spacer (91-03)] |
techtalk:evo:engmech04b [2021/07/23 03:57] hippysmack [Middle Rocker Box Spacer (91-03)] |
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| |{{:techtalk:evo:engmech:rocker_box_clearance_3_by_aswracing.jpg?direct&300|}}|{{:techtalk:evo:engmech:rocker_box_clearance_4_by_aswracing.jpg?direct&300|}}|{{:techtalk:evo:engmech:claying_the_upper_rocker_box_by_new2hdfrank.jpg?direct&300|}}| | |{{:techtalk:evo:engmech:rocker_box_clearance_3_by_aswracing.jpg?direct&300|}}|{{:techtalk:evo:engmech:rocker_box_clearance_4_by_aswracing.jpg?direct&300|}}|{{:techtalk:evo:engmech:claying_the_upper_rocker_box_by_new2hdfrank.jpg?direct&300|}}| | ||
| - | ===== Middle Rocker Box Spacer (91-03) ===== | ||
| - | 86-90 engines do not have a crankcase breather valve incorporated into the rocker boxes so this won't work for those year models. \\ | ||
| - | **This is a mod to (possibly help) curtail the issue of puking oil out the breathers**. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?page=5&t=1958462)) \\ | ||
| - | However, the first answer would address other known factors for wet sumping. \\ | ||
| - | This mod consists of; \\ | ||
| - | Chamfering the umbrella hole to 60 degrees (included angle) and drilling out the existing drain back hole to 1/8". \\ | ||
| - | To the extent the drain back hole is enlarged, it bypasses the umbrella valve back into the boxes. \\ | ||
| - | Maybe 1/8" isn't enough to cause an issue. \\ | ||
| - | The umbrella valve is what keeps the air inhalation/exhalation to a minimum. \\ | ||
| - | And inhalation/exhalation is what carries oil out the breathers so you don't want to bypass it any more than necessary. \\ | ||
| - | |||
| - | You could probably do the chamfer, but not the drain hole enlargement. Then, if you still have the issue, you could also drill out the drain hole. \\ | ||
| - | |||
| - | The rocker box middles use the same casting for both the front and rear cylinder. And there's a facility for the umbrella valve on both ends of each middle spacer. \\ | ||
| - | So you can try this, and if it doesn't work, just move the umbrella valve to the other end. \\ | ||
| - | And use the rocker box middle on the other cylinder. In other words, this mod is undo-able... once anyway. \\ | ||
| - | |||
| - | The umbrella hole is the one in the middle of the picture below. \\ | ||
| - | The drain back hole is the tiny little hole to the right of the sideways 13 in the picture. \\ | ||
| - | |||
| - | {{:techtalk:evo:engmech:rocker_box_mod_by_aswracing.jpg?direct&300|}} ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?page=5&t=1958462)) \\ | ||
| - | |||
| - | **Another suggestion is to enlarge the tiny oil drain from ~.070 to .09375 and add threaded inserts as oil standoffs**. ((toe of the XLFORUM http://xlforum.net/forums/showthread.php?p=4641942#post4641942)) ((http://xlforum.net/forums/showthread.php?t=1703706&page=2)) \\ | ||
| - | Looking at the pictures below, you can see 3 roughly oval shaped holes in the corners of the middle rocker box. \\ | ||
| - | (2 per rocker box, only 1 is used per cylinder on the each intake side) | ||
| - | |||
| - | With each downstroke, the air in the crankcase is forced past the umbrella valve carrying oil mist with it. \\ | ||
| - | The oil is supposed it settle out in this little chamber and drain back to the heads thru the tiny hole in the cavity. \\ | ||
| - | |||
| - | Slightly enlarging the little hole lets the oil drain back easier. Air that enters this oval(ish) chamber has to go somewhere. \\ | ||
| - | So it goes out the big hole on top, thru the breather bolts and out. \\ | ||
| - | The threaded insert just provides a lip around the hole. \\ | ||
| - | So any oil that drops out of suspension around the hole won't drain out the breather. It just makes it a little bit harder for oil to go out the breather. \\ | ||
| - | The inserts below were left overs from another project. You can use anything that does the same thing. \\ | ||
| - | |||
| - | You can buy a product online called "Slobber Stoppers". [[https://www.ebay.com/itm/200917426709]] \\ | ||
| - | It comes with threaded barrels similar to the threaded inserts below to eliminate oil mist from getting into the air cleaner. | ||
| - | |||
| - | {{:techtalk:evo:engmech:rocker_box_mod_3_by_toe.jpg?direct&300|}} ((toe of the XLFORUM http://xlforum.net/forums/showthread.php?p=4641942#post4641942)) {{:techtalk:evo:engmech:rocker_box_mod_2_by_toe.jpg?direct&300|}} ((toe of the XLFORUM http://xlforum.net/forums/showthread.php?p=4641942#post4641942)) | ||
| ===== Lower Rocker Box / Cover (All) ===== | ===== Lower Rocker Box / Cover (All) ===== | ||
