IH: Oiling & Lubrication

Engine Oil Routes

Right Crankcase Feed Galley

Top End Oiling

Rocker Arm / Valve Oiling

Rocker arm shaft. 1) Oil flow. 2) Exhaust valve squirter. 3)

Rocker Box Oiling

Oil travels in a passage between the two rocker arm shafts (big end).
The oil line comes from underneath into one shaft bore on the pushrod side in each rocker box.
There is a rifle drilled hole between the rocker arm shafts in each box that connects the two for oil passage.
Each hole is plugged off on the outside of the box.

Front rocker box oiling.
Rocker Boxes on 69 model. 4)

Bottom End Oiling

Pinion shaft and Crank Pin

Cam Cover Bushings

Cam Cover \ Gasket

Case Oiling and Drainage

73-Up right case half 5)

Splash

Oil Pump Scavenge

See also the IH Oil Pump section of the Sportsterpedia.

'77 and Later Cases

The “drain plug” on the bottom of the case is simply a threaded plug that caps the oil scavenging passageway. 6)
The MoCo drilled from the bottom of the case to the horizontal oil passage in the gearcase.
This connects the crankcase sump oil to the scavenge port of the oil pump and the hole is plugged on the bottom.

From inside the case with the plug removed from the scavenge passage;
In the second pic below, you can see that the threads, from the tap, have been machined farther up into this hole.
This is the oil passage from the sump to the scavenge pump.
Oil from cylinder drains, crankpin, pushrods and cam chest that collects in the sump is fed to the pump by crankcase pressure and pump suction through this hole.

Scavenge passage on 77 engines 7)

Gravity


1) , 3)
photo by jmmarks70 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1774605
2)
photo by jmmarks70 of the XLFORUM - annotated by Hippysmack http://xlforum.net/forums/showthread.php?t=1774605
5)
photo by ironheadjunkie of the XLFORUM http://xlforum.net/forums/showthread.php?t=1421916&page=2
7)
photos by bobbystat of the XLFORUM http://xlforum.net/forums/showthread.php?t=1950691
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