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techtalk:ih:engmech07 [2019/10/11 23:40] hippysmack |
techtalk:ih:engmech07 [2019/12/04 04:30] hippysmack [Sub Documents] |
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Documents from HD Racing from the period show no HP gain between the 2 systems when the breather is properly timed ( which didn't happen a lot). \\ | Documents from HD Racing from the period show no HP gain between the 2 systems when the breather is properly timed ( which didn't happen a lot). \\ | ||
===== 76< Timed Breather Valve ===== | ===== 76< Timed Breather Valve ===== | ||
- | The rotary breather valve is timed to open on the downstroke of the pistons. ((1960 HD FSM pg 3a-15)) \\ | + | ==== Sub Documents ==== |
+ | * [[techtalk:ih:engmech07a|Timing the 76< Breather Valve]] | ||
+ | |||
+ | The rotary breather valve functions to relieve pressure in the crankcase caused by the downstroke of the pistons and it controls the flow of oil in the lubrication system. \\ | ||
+ | It is timed to open on the downstroke of the pistons. ((1960 HD FSM pg 3a-15)) \\ | ||
This allows crankcase exhaust air pressure to expel the scavenge oil from the crankcase breather oil trap into the gearcase. \\ | This allows crankcase exhaust air pressure to expel the scavenge oil from the crankcase breather oil trap into the gearcase. \\ | ||
- | The breather valve closes on piston upstroke, creating vacuum in the crankcase. \\ | + | The breather valve then closes on piston upstroke, creating vacuum in the crankcase. \\ |
+ | Crankcase exhaust air from the gearcase is sent out the breather tube. \\ | ||
+ | Any oil still in suspension with the air on the way to the breather tube is separated by an oil slinger on the generator drive gear. \\ | ||
+ | |||
+ | A street oil pump has 2 slots and is driven at 1/2 engine speed. ((thefrenchowl of the XLFORUM http://xlforum.net/forums/showthread.php?t=448751)) \\ | ||
+ | A racing oil pump has 4 slots and is driven at 1/4 engine speed. \\ | ||
+ | All 4 stroke engines takes two revolutions before you come back to the timing marks being all aligned. | ||
How the volume compares when the breather opens as to when it closes: ((Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=3)) \\ | How the volume compares when the breather opens as to when it closes: ((Dr Dick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=3)) \\ | ||
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|{{:techtalk:ih:engmech:cc_flow_6_by_dr_dick.jpg?direct&300|}}|{{:techtalk:ih:engmech:cc_flow_7_by_dr_dick.jpg?direct&300|}}|{{:techtalk:ih:engmech:cc_flow_8_by_dr_dick.jpg?direct&300|}}| | |{{:techtalk:ih:engmech:cc_flow_6_by_dr_dick.jpg?direct&300|}}|{{:techtalk:ih:engmech:cc_flow_7_by_dr_dick.jpg?direct&300|}}|{{:techtalk:ih:engmech:cc_flow_8_by_dr_dick.jpg?direct&300|}}| | ||
+ | \\ | ||
+ | There are only 3 rotor and tower slot widths for all 1937-76 4-cam engines (45, K, KH, XL, UL), which determine the complete breather timing interval. ((kitabel of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=87)) \\ | ||
+ | - Rotor .375" (88°) + tower .34375" (81°) = 169°: \\ all non-R 1937-71 engines; the exact opening-closing points vary between engines; 1952-71 K &c. slots are taller than 45 & UL. | ||
+ | - Rotor .594" (146°) + tower .34375" (81°) = 227°: 1972-76 XL; these slots are also taller than 45 & UL. | ||
+ | - Rotor .214" (99°) + tower .269 (125°) = 224°: all 1954-? KR, KHR, XLR (many mods to this) | ||
===== 77-78 Breather Valve ===== | ===== 77-78 Breather Valve ===== | ||
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{{:techtalk:ih:engmech:83_xlx_crankcase_vent_mod_by_83xlx.jpg?direct&300|}} ((photo by 83XLX of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather&page=3)) | {{:techtalk:ih:engmech:83_xlx_crankcase_vent_mod_by_83xlx.jpg?direct&300|}} ((photo by 83XLX of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather&page=3)) | ||
- | ===== Breather Valve Alternatives ===== | + | ====== Breather Valve Alternatives ====== |
* There is a product called a Krankvent that can be plumbed into the lower, 6 o’clock position as an alternative to a stock foo-foo valve. But they are not cheap. | * There is a product called a Krankvent that can be plumbed into the lower, 6 o’clock position as an alternative to a stock foo-foo valve. But they are not cheap. |