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techtalk:ref:svcproc22 [2019/12/12 01:20] hippysmack [Find TDC (compression) Using the Timing Mark on the Flywheel (57-03)] |
techtalk:ref:svcproc22 [2024/01/22 05:46] hippysmack |
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| This is often referred to as TDC on Compression Stroke or TDC Compression. \\ | This is often referred to as TDC on Compression Stroke or TDC Compression. \\ | ||
| - | * The window in time where both valves are completely closed begins on the compression stroke, with the closing of the intake valve. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717577)) | + | * The window in time where both valves are completely closed begins on the compression stroke, with the closing of the intake valve. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160094-compression-tdc-please-help-me-find-it?t=1717577)) |
| * Both valves stay closed through the rest of the compression stroke, and then most of the following power stroke, at which point the exhaust valve opens. | * Both valves stay closed through the rest of the compression stroke, and then most of the following power stroke, at which point the exhaust valve opens. | ||
| * Compression TDC sits just about half way in between those two events, so it makes a good reference point. | * Compression TDC sits just about half way in between those two events, so it makes a good reference point. | ||
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| In terms of the piston position, there's no difference between compression TDC and overlap TDC. \\ | In terms of the piston position, there's no difference between compression TDC and overlap TDC. \\ | ||
| The piston doesn't do anything different. \\ | The piston doesn't do anything different. \\ | ||
| - | Compression TDC and exhaust (overlap) TDC are only different by virtue of what the valvetrain is doing. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717577)) | + | Compression TDC and exhaust (overlap) TDC are only different by virtue of what the valvetrain is doing. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160094-compression-tdc-please-help-me-find-it?t=1717577)) |
| - | * **With the piston on TDC of the compression stroke**: (otherwise referred to as "TDC Compression") ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717577)) | + | * **With the piston on TDC of the compression stroke**: (otherwise referred to as "TDC Compression") ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160094-compression-tdc-please-help-me-find-it?t=1717577)) |
| * Both valves are closed. | * Both valves are closed. | ||
| * Both corresponding cams are on their base circle. | * Both corresponding cams are on their base circle. | ||
| * The cams and lifters are producing the least amount of pressure upward toward the rockers and valves. | * The cams and lifters are producing the least amount of pressure upward toward the rockers and valves. | ||
| * When the lifters bleed off their oil, there will little to no pressure toward the rockers and valves. | * When the lifters bleed off their oil, there will little to no pressure toward the rockers and valves. | ||
| - | * **With the piston on TDC of the exhaust stroke**: (otherwise referred to as "TDC Overlap") ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717577)) | + | * **With the piston on TDC of the exhaust stroke**: (otherwise referred to as "TDC Overlap") ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160094-compression-tdc-please-help-me-find-it?t=1717577)) |
| * Both valves are slightly open. | * Both valves are slightly open. | ||
| * Both corresponding cams are on their respective side ramps. | * Both corresponding cams are on their respective side ramps. | ||
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| ====== Finding True TDC ====== | ====== Finding True TDC ====== | ||
| - | + | \\ | |
| - | + | ||
| ===== Accuracy of True TDC Using Only A Dial Indicator ===== | ===== Accuracy of True TDC Using Only A Dial Indicator ===== | ||
| There are several ways to find TDC. \\ | There are several ways to find TDC. \\ | ||
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| * [[techtalk:ih:engctl01#timing_marks|Click here for stock 57-85 TDC symbol identification]]. | * [[techtalk:ih:engctl01#timing_marks|Click here for stock 57-85 TDC symbol identification]]. | ||
| * [[techtalk:evo:engctl01#ignition_timing_-_all_models_thru_2003|Click here for stock 86-03 TDC symbol identification]]. | * [[techtalk:evo:engctl01#ignition_timing_-_all_models_thru_2003|Click here for stock 86-03 TDC symbol identification]]. | ||
| - | * If you've upgraded to a 2004 or later flywheel assembly, (on 03 and prior engines) you'll have to [[techtalk:ref:engmech01c|make your own TDC mark]] on these if you need one. \\ (this procedure can also be used to create the advance timing mark) | + | * If you've upgraded to a 2004 or later flywheel assembly, (on 03 and prior engines) you'll have to [[techtalk:ref:engmech01l|make your own TDC mark]] on these if you need one. \\ (this procedure can also be used to create the advance timing mark) |
