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--- techtalk:ih:engmech07 [2019/07/11 03:58]
hippysmack [77> Breather Valve (or Foo Foo Valve)]
+++ techtalk:ih:engmech07 [2019/12/04 04:20]
hippysmack [Sub Documents]
@@ Line 86: / Line 86: @@
 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 =====
+==== Sub Documents ====
+  * [[techtalk:ih:engmech07a|Timing the 76< Breather Valve]]
 The rotary breather valve 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. \\
 The breather valve 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)) \\
@@ Line 121: / Line 130: @@
 |{{: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> Breather Valve (or Foo Foo Valve) =====
 WHAT IS IT?
   * The slang term "FooFoo" comes from the annoying sound that it makes when it gets clogged up with oil residue. ((IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1332902&page=3))
-  * The engine breather, or crankcase vent as Harley sometimes calls it, is to allow air out of the lower crankcase, but not in, as the pistons rise and fall. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948)) \\ Without some kind of controlled breather, the lower end would become a 1,000cc air compressor, robbing the engine of several horsepower. \\ Old time tuners like Jerry Branch, Tom Sifton and Dick O’Brien paid much attention to the engine breather because they knew it could give them extra horsepower if set up right.
+  * The engine breather (or crankcase vent) is to allow air out of the lower crankcase, but not in, as the pistons rise and fall. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948)) \\ Without some kind of controlled breather, the lower end would become a 1,000cc air compressor, robbing the engine of several horsepower. \\ Old time tuners like Jerry Branch, Tom Sifton and Dick O’Brien paid much attention to the engine breather. \\ They knew it could give them extra horsepower if set up right.
   *  One thing not to do with an engine breather is to simply plumb a hose to the crankcase without some kind of one-way valve or timed breather valve. \\ It is commonly done, but it wastes power and is not good for your engine.
-WHERE IS IT? ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948))
+WHERE IS IT? ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=518948)) \\
   * **Pre-1977**
-      * There is a timed breather valve built into the oil pump drive, which vents 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 metal disc on the end of the generator drive gear centrifugally separates oil from the air as it is discharged overboard.
+      * There is a timed breather valve built into the oil pump drive, which vents 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 metal disc on the end of the generator drive gear centrifugally separates oil from the air as it is discharged overboard.
-  * **1977-78 only** ((Hopper)) ((HD Service Bulletin #M-708 dated December 1, 1976))
+  * **1977-78 only** ((Hopper)) ((HD Service Bulletin #M-708 dated December 1, 1976)) \\
-      * The timed breather on the oil pump drive was dropped. A new design breather valve (24633-77) was used in late 1977 model XL/XLCH/XLT engines produced around October 15, 1976. All 1000cc engine numbers (3A, 4A or 2G) 27940H7 and above had the new breather valve. It serves the same function as the gear driven breather valve used on 1976 and earlier engines to maintain a partial vacuum in the engine and prevent oil leakage. Due to it's improvements in doing so, it was suggested to be retrofitted to all 1977 XL & XLCH engines.
+      * The timed breather on the oil pump drive was dropped. \\ A new design breather valve (24633-77) was used in late 1977 model XL/XLCH/XLT engines produced around October 15, 1976. \\ All 1000cc engine numbers (3A, 4A or 2G) 27940H7 and above had the new breather valve. \\ It serves the same function as the gear driven breather valve used on 1976 and earlier engines to maintain a partial vacuum in the engine and prevent oil leakage. \\ Due to it's improvements in doing so, it was suggested to be retrofitted to all 1977 XL & XLCH engines.
-      * The one-way valve is contained in a fitting which screws into the gear-case cover below the generator mounting boss. The existing breather outlet pipe screws into the bottom of the new fitting. The outlet pipe because of its lower position must be directed outside (instead of inside) the frame tube. The rubber hose at the pipe outlet must no longer be used.
+      * The one-way valve is contained in a fitting which screws into the gear-case cover below the generator mounting boss. \\ The existing breather outlet pipe screws into the bottom of the new fitting. \\ The outlet pipe, because of its lower position, must be directed outside (instead of inside) the frame tube. \\ The rubber hose at the pipe outlet must no longer be used.
       * Because of the higher vacuum existing in the engines equipped with this new breather valve, a higher pressure oil pump check valve (26435-76A) was installed in L1977 oil pumps at the same time to provide higher oil pressure at the oil pressure light switch.
-      * The new valve opens at 4-6 PSI whereas the old valve opens at 2-4 PSI. Pumps having the new valve are identified with a green dot. The existing 0-ring (26433- 77) was used for both new and old valves.
+      * The new valve opens at 4-6 PSI whereas the old valve opens at 2-4 PSI. \\ Pumps having the new valve are identified with a green dot. \\ The existing 0-ring (26433- 77) was used for both new and old valves.
-      *  An external non-return valve was plumbed into the 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. Searching the XLFORUM for __foo foo valve__ or __foo-foo__ will lead to extensive discussions of this mystical device.
+      *  An external non-return valve was plumbed into the 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. \\ Searching the XLFORUM for __foo foo valve__ or __foo-foo__ will lead to extensive discussions of this mystical device.
 |{{:techtalk:ih:oil:77-78_ext_foo_foo_valve_1_by_hopper.jpg?direct&300|}}|{{:techtalk:ih:oil:77-78_ext_foo_foo_valve_2_by_hopper.jpg?direct&300|}}|{{:techtalk:ih:oil:77-78_ext_foo_foo_valve_3_by_hopper.jpg?direct&300|}}|
 |  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. 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. \\
 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. \\
 {{: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))
@@ Line 179: / Line 195: @@
 {{: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.
   * 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.

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