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techtalk:ref:engmech04k [2020/10/03 06:05] hippysmack created |
techtalk:ref:engmech04k [2020/10/09 02:24] hippysmack [Breather Valves (1957-Up)] |
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- | ===== Breather Valves (1957-Up) ===== | + | [[:techtalk:menu|{{ :techtalk:gototechnicalmenu.jpg|}}]] |
+ | ====== REF: Engine Mechanicals - Sub-04K ====== | ||
+ | \\ | ||
+ | ====== Breather Valves (1957-Up) ====== | ||
See the respective sections in the Sportsterpedia for the different breather valves used on Sportsters. \\ | See the respective sections in the Sportsterpedia for the different breather valves used on Sportsters. \\ | ||
* [[techtalk:ih:engmech07|IH Crankcase Ventilation (1957-1985)]] \\ | * [[techtalk:ih:engmech07|IH Crankcase Ventilation (1957-1985)]] \\ | ||
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**1957-1976 models**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | **1957-1976 models**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | ||
- | There is a timed breather valve built into the oil pump drive, which vents crankcase pressure into the cam timing chest. \\ | + | There is a timed breather valve built into the oil pump drive, which vents both oil and crankcase pressure into the cam timing chest. \\ |
A six-inch metal tube hanging down from the timing cover near the generator drive, at the 6 o’clock position vents that controlled pressure to atmosphere. \\ | A six-inch metal tube hanging down from the timing cover near the generator drive, at the 6 o’clock position vents that controlled pressure to atmosphere. \\ | ||
A metal gear or washer on the end of the generator drive gear centrifugally separates oil from the air as it is discharged overboard. \\ | A metal gear or washer on the end of the generator drive gear centrifugally separates oil from the air as it is discharged overboard. \\ | ||
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The rotary breather valve on the oil pump that is timed to open on the downstroke of the pistons. ((1960 HD FSM pg 3a-15)) \\ | The rotary breather valve on the oil pump that is timed to open on the downstroke of the pistons. ((1960 HD FSM pg 3a-15)) \\ | ||
This allows crankcase exhaust air pressure and scavenge oil in the crankcase to be expelled from the crankcase to the breather oil trap and into the gearcase. \\ | This allows crankcase exhaust air pressure and scavenge oil in the crankcase to be expelled from the crankcase to the breather oil trap and into the gearcase. \\ | ||
The breather valve closes during piston upstroke, creating a controlled amount of vacuum in the crankcase. \\ | The breather valve closes during piston upstroke, creating a controlled amount of vacuum in the crankcase. \\ | ||
+ | **The 1952-1971** breather valve opens at 77° (ATDC) and closes 67° (ABDC). \\ | ||
+ | **The 1972-1976** breather valve opens 20°-25° (ATDC) and closes 85°-90° (ABDC), less duration than the 57-71 breather. \\ | ||
+ | |||
**1977-78 models only**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | **1977-78 models only**: ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948&highlight=cam+chest+breather)) \\ | ||
The timed breather on the oil pump drive was dropped. \\ | The timed breather on the oil pump drive was dropped. \\ | ||
- | Without the breather gear that means you less control of the oil / air density in the crankcase. | + | Without the breather gear that means you have less control of the oil / air density in the crankcase. \\ |
An external non-return valve was plumbed into the breather vent tube sticking down from the timing cover at the generator drive. \\ | An external non-return valve was plumbed into the breather vent tube sticking down from the timing cover at the generator drive. \\ | ||
This allows air out, but not in. It is sometimes referred to as the foo-foo valve. \\ | This allows air out, but not in. It is sometimes referred to as the foo-foo valve. \\ | ||
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A breather baffle tube system was incorporated into the cam cover in the area behind the oil filter and the slinger washer is no longer used. \\ | A breather baffle tube system was incorporated into the cam cover in the area behind the oil filter and the slinger washer is no longer used. \\ | ||
The baffle tube has a one way umbrella valve mounted into it. Crankcase exhaust (air and oil mist) is routed to the breather baffle at the front of the gearcase. \\ | The baffle tube has a one way umbrella valve mounted into it. Crankcase exhaust (air and oil mist) is routed to the breather baffle at the front of the gearcase. \\ | ||
- | Oil is separated from the air pressure by the one-way umbrella valve. The cam cover has an oil drain back valve built into the breather valve compartment. \ | + | Oil is separated from the air pressure by the one-way umbrella valve. The cam cover has an oil drain back valve built into the breather valve compartment. \\ |
This allows accumulated oil that gets past the valve to drain back into the gearcase through that drain hole. \\ | This allows accumulated oil that gets past the valve to drain back into the gearcase through that drain hole. \\ | ||
The air is then routed into the rear of the air cleaner via an oil hose to the gearcase outlet. \\ | The air is then routed into the rear of the air cleaner via an oil hose to the gearcase outlet. \\ | ||
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+ | 57-76 engines breath and scavenge oil from the same oil galley in the rear of the sump. \\ | ||
+ | <blockquote>The shallow sump, timed breather system, comes from the aviation world of old. ((mrmom9r of the XLFORUM http://xlforum.net/forums/showthread.php?t=1204854&page=4)) \\ | ||
+ | Piston driven aircraft had to be able to evacuate the oil from the crankcase regardless of engine altitude and that system does that. \\ | ||
+ | At the time Harley adapted that system they were copying the highest engine technology of the day. \\ | ||
+ | They just took too long to abandon it as technology advanced. \\ | ||
+ | Documents from HD Racing from the period show no HP gain between the 2 ironhead systems when the breather is properly timed ( which didn't happen a lot). \\ | ||
+ | </blockquote> | ||
+ | |||
+ | The rotary breather valve is integrated with the oil pump. The gear on top of the valve also operates the oil pump. \\ | ||
+ | The breather valve connects the flywheel area to the gearcase. \\ | ||
+ | |||
+ | 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 engine rotation and opens 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. \\ | ||
+ | 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. \\ | ||
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+ | |Left is the unmodified 1/4 speed R \\ valve. Right is the 1000 stock.|R model is the left one.| | ||
+ | |{{:techtalk:ih:engmech:cc_flow_4_by_dr_dick.jpg?direct&200|}}|{{:techtalk:ih:engmech:cc_flow_5_by_dr_dick.jpg?direct&300|}}| | ||
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+ | [[:techtalk:menu|{{:techtalk:gototechnicalmenu.jpg|}}]] |