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techtalk:evo:engmech02c [2022/09/05 06:46] – [Hydraulic Lifter - Mechanical and Hydraulic Operation] hippysmack | techtalk:evo:engmech02c [2024/05/22 04:33] (current) – [Hydraulic Lifter - Mechanical and Hydraulic Operation] hippysmack | ||
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====== EVO: Engine Mechanicals - Sub-02C ====== | ====== EVO: Engine Mechanicals - Sub-02C ====== | ||
====== Hydraulic Lifter - Mechanical and Hydraulic Operation ====== | ====== Hydraulic Lifter - Mechanical and Hydraulic Operation ====== | ||
- | The hydraulic lifters used in HD motors have about .200 of (useable) plunger travel ((aswracing of the XLFORUM | + | The hydraulic lifters used in HD motors have about .200 of (useable) plunger travel ((aswracing of the XLFORUM |
As long as it's preloaded between about .050 and .150, it adjusts itself properly. So in other words, there' | As long as it's preloaded between about .050 and .150, it adjusts itself properly. So in other words, there' | ||
The lifter will automatically adjust it's length to make it all work properly. \\ | The lifter will automatically adjust it's length to make it all work properly. \\ | ||
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System oil pressure goes all the way thru the lifters to the rocker boxes. \\ | System oil pressure goes all the way thru the lifters to the rocker boxes. \\ | ||
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Examining internal lifter oil paths from the lifter bore to the rocker arms will show some of these dynamics. \\ | Examining internal lifter oil paths from the lifter bore to the rocker arms will show some of these dynamics. \\ | ||
- | {{:techtalk:ref:oil: | + | {{techtalk:evo:engmech: |
\\ | \\ | ||
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Disclaimer: \\ | Disclaimer: \\ | ||
- | The main oil inlet in the lifter body has been moved from the from to the left side for clarity of the feed path. \\ | + | The main oil inlet in the lifter body has been moved to the left side for clarity of the feed path. \\ |
Also, the oil inlet is slightly lower than the actual part but operation and paths are the same. \\ | Also, the oil inlet is slightly lower than the actual part but operation and paths are the same. \\ | ||
{{: | {{: | ||
+ | |||
====== Oil to the lifter body ====== | ====== Oil to the lifter body ====== | ||
System oil pressure is fed through the lifter bores into the outer oil band that circles the lifter body. \\ | System oil pressure is fed through the lifter bores into the outer oil band that circles the lifter body. \\ | ||
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In the drawing below, dims were taken from a 1998 1200S lifter and bore showing that oil feed is never blocked to the lifter. \\ | In the drawing below, dims were taken from a 1998 1200S lifter and bore showing that oil feed is never blocked to the lifter. \\ | ||
The cams are Andrews N-4s so actual lift may vary. However, the feed hole in the bore should be the same for at least 1991-1999 Sportsters. \\ | The cams are Andrews N-4s so actual lift may vary. However, the feed hole in the bore should be the same for at least 1991-1999 Sportsters. \\ | ||
- | {{: | + | {{: |
====== Oil to the plunger reservoir ====== | ====== Oil to the plunger reservoir ====== | ||
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The plunger is free to rotate invariably both during assembly and when not under load. \\ | The plunger is free to rotate invariably both during assembly and when not under load. \\ | ||
- | {{:techtalk: | + | {{techtalk: |
====== Role of the check disc ====== | ====== Role of the check disc ====== | ||
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The downward force of oil in the plunger reservoir opens the check disc toward the lower chamber. \\ | The downward force of oil in the plunger reservoir opens the check disc toward the lower chamber. \\ | ||
The (now open bottom) plunger is moving down into the lower chamber filled with oil. \\ | The (now open bottom) plunger is moving down into the lower chamber filled with oil. \\ | ||
- | Some of the oil in the lower chamber is squeezed up past the open check disc into the plunger reservoir. \ | + | Some of the oil in the lower chamber is squeezed up past the open check disc into the plunger reservoir. |
With the check disc open, the lower chamber volume decreases as the plunger is continuously forced toward it by increasing engine valve spring pressure. \\ | With the check disc open, the lower chamber volume decreases as the plunger is continuously forced toward it by increasing engine valve spring pressure. \\ | ||
This increases oil pressure in the lower chamber forcing the check disc to close toward the plunger. \\ | This increases oil pressure in the lower chamber forcing the check disc to close toward the plunger. \\ | ||
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And the pressure chamber is what actually raises the engine valves. | And the pressure chamber is what actually raises the engine valves. | ||
- | {{:techtalk:ref:oil: | + | {{techtalk:evo:engmech: |