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techtalk:ih:engmech07 [2019/07/11 04:21]
hippysmack [77> Breather Valve (or Foo Foo Valve)]
techtalk:ih:engmech07 [2019/12/04 04:30] (current)
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 =====
-===== 77Breather Valve (or Foo Foo Valve) ​=====+
  
 WHAT IS IT? WHAT IS IT?
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 |  77-78 Crankcase Ventilation Valve ((photo by Hopper of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=1960632)) ​ | |  77-78 Crankcase Ventilation Valve ((photo by Hopper of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=1960632)) ​ |
  
-  * **1979-E1982**.+===== 1979-E1982 ​===== 
       * The external foo-foo valve and the six-inch metal vent tube at the front of the timing cover were done away with. \\ Instead, a one-way foo-foo valve was built inside the timing cover (26909-79A),​ (26909-82). \\ A rubber breather hose then ran from the generator drive area of the timing cover, at the 9 o’clock position. \\ It connected to the stock air filter so that any oil mist was fed back through the engine, making the EPA pollutocrats more happier. \\ (than they were with the idea of engine oil spraying out into the atmosphere) \\ The generator had a (1-5/​8"​ O.D.) oil separator washer on the end of the armature shaft. ((HD Service Bulletin #M-848 dated April 9, 1982))       * The external foo-foo valve and the six-inch metal vent tube at the front of the timing cover were done away with. \\ Instead, a one-way foo-foo valve was built inside the timing cover (26909-79A),​ (26909-82). \\ A rubber breather hose then ran from the generator drive area of the timing cover, at the 9 o’clock position. \\ It connected to the stock air filter so that any oil mist was fed back through the engine, making the EPA pollutocrats more happier. \\ (than they were with the idea of engine oil spraying out into the atmosphere) \\ The generator had a (1-5/​8"​ O.D.) oil separator washer on the end of the armature shaft. ((HD Service Bulletin #M-848 dated April 9, 1982))
  
 Here is a pic of IronMick'​s internal foo-foo in his post-79 model on the left. \\ Here is a pic of IronMick'​s internal foo-foo in his post-79 model on the left. \\
 You can see the 9 oclock fitting and the 6 oclock fitting both enter the same cavity. \\ You can see the 9 oclock fitting and the 6 oclock fitting both enter the same cavity. \\
-{{techtalk:​ih:​oil:​ihcamcoverxlf.jpg?​direct&​250|}} ((photo by ryder rick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=518948&​page=2)) \\+The oil slinger is the big fat washer on the end of the generator in the (R) pic below. \\ 
 +{{techtalk:​ih:​oil:​ihcamcoverxlf.jpg?​direct&​250|}} ((photo by ryder rick of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=518948&​page=2)) {{:​techtalk:​ih:​engmech:​oil_slinger_by_screwloose.jpg?​direct&​300|}} ((photo by Screwloose of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1979566&​highlight=float&​page=5)) \\
  
 Here's the reed valve and the back side. \\ Here's the reed valve and the back side. \\
 {{:​techtalk:​ih:​engmech:​79_breather_valve_by_tobybott.jpg?​direct&​350|}} ((photo by tobybott of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=982127&​highlight=breather#​post982127)) {{:​techtalk:​ih:​engmech:​reed_valve_by_lodkolv.jpg?​direct&​300|}} ((photo by lodkolv of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=113861&​highlight=breather&​page=2)) \\ {{:​techtalk:​ih:​engmech:​79_breather_valve_by_tobybott.jpg?​direct&​350|}} ((photo by tobybott of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=982127&​highlight=breather#​post982127)) {{:​techtalk:​ih:​engmech:​reed_valve_by_lodkolv.jpg?​direct&​300|}} ((photo by lodkolv of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=113861&​highlight=breather&​page=2)) \\
  
-  * **L1982-1985**+===== L1982-1985 ​===== 
       * The internal crankcase breather valve was redesigned to incorporate a rubber umbrella valve attached to the base plate along with a larger diameter (1-3/​4"​ O.D.) oil separator washer on the generator armature. ((HD Service Bulletin #M-848 dated April 9, 1982))       * The internal crankcase breather valve was redesigned to incorporate a rubber umbrella valve attached to the base plate along with a larger diameter (1-3/​4"​ O.D.) oil separator washer on the generator armature. ((HD Service Bulletin #M-848 dated April 9, 1982))
  
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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))
  
-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.
   * Automotive PCV valves are not really made to handle the revs or air volumes of a Harley. While a car engine is bigger, it has one piston coming down while one goes up, so not much change in internal crankcase volume, so not much breathing to be done. A Harley has two pistons and rods on one crankpin, so is one giant air compressor.   * Automotive PCV valves are not really made to handle the revs or air volumes of a Harley. While a car engine is bigger, it has one piston coming down while one goes up, so not much change in internal crankcase volume, so not much breathing to be done. A Harley has two pistons and rods on one crankpin, so is one giant air compressor.