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techtalk:evo:oil01 [2019/06/22 16:47] hippysmack [Oil Pump Feed] |
techtalk:evo:oil01 [2019/06/22 22:51] hippysmack [Crankcase Pressure] |
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===== Crankcase Pressure ===== | ===== Crankcase Pressure ===== | ||
+ | See also [[techtalk:ref:engmech04|Evo Crankcase Pressure and Engine Breathing]] in the REF section of the Sportsterpedia. \\ | ||
+ | |||
Crankcase air pressure is mainly generated by the up and down movement of the pistons. \\ | Crankcase air pressure is mainly generated by the up and down movement of the pistons. \\ | ||
The downstroke of the piston causes the volume underneath the pistons to decrease which puts pressure on the oil in the sump. ((cjburr of the XLFORUM http://xlforum.net/forums/showthread.php?t=73243&page=3)) \\ | The downstroke of the piston causes the volume underneath the pistons to decrease which puts pressure on the oil in the sump. ((cjburr of the XLFORUM http://xlforum.net/forums/showthread.php?t=73243&page=3)) \\ | ||
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* A drilled passage also connects the feed galley down to squirt excess feed pressure to #2 cam gear. | * A drilled passage also connects the feed galley down to squirt excess feed pressure to #2 cam gear. | ||
* 04-Up engines: | * 04-Up engines: | ||
- | * Additional, oil is fed from the feed galley (through a drilled passage) to the piston squirters. | + | * In addition, oil is fed from the feed galley (through a drilled passage) to the piston squirters. |
| 91-97 Oil Pump Oiling Paths ((photo by Hippysmack)) | 98 and Up Oil Pump Oiling Paths ((photo by bsaman of the XLFORUM http://xlforum.net/forums/showthread.php?t=691283&page=2)) | | | 91-97 Oil Pump Oiling Paths ((photo by Hippysmack)) | 98 and Up Oil Pump Oiling Paths ((photo by bsaman of the XLFORUM http://xlforum.net/forums/showthread.php?t=691283&page=2)) | | ||
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Oil pump pressure is always present in the cam cover with the engine running. \\ | Oil pump pressure is always present in the cam cover with the engine running. \\ | ||
That is also a deceiving statement. Pump pressure runs through internal cavities in the cover to get from the top to the bottom of the cover and to the pinion shaft. \\ | That is also a deceiving statement. Pump pressure runs through internal cavities in the cover to get from the top to the bottom of the cover and to the pinion shaft. \\ | ||
- | However, oil pump pressure does not dump directly into the cam chest from the cover. \\ | + | However, oil pump pressure does not dump directly into the cam chest from the cover normally. \\ |
+ | On 86-91 engines with the oil pressure regulator, the regulator dumps excess oil pressure into the gearcase until the high pressure condition subsides. \\ | ||
+ | 92 and Up engines do not have this spring actuating pressure regulator but they still have a pressure bleed off passage in the main feed galley. \\ | ||
+ | This tiny hole from the feed galley bleeds off excess feed pressure into the gearcase and onto the #2 cam gear. \\ | ||
=== 86-90 engines === | === 86-90 engines === |