S&S Cycle Billet Oil Pump for Big Twin Engines - Manual (Page 20)

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NOTES:
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Low oil pressure is often blamed on oil pump when actual cause is worn bushings or another internal component. A new oil pump will not correct
problems caused by worn parts and excessive operating clearances. If low oil pressure exists after new oil pump is installed, check bearing clearances
and other possible causes such as installation of different gear cover, tappet guides, etc.
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With engine hot, typical oil pressure reading is 3-4 PSI at 1000 RPM idle, 12-15 PSI at normal highway speeds or approximately 2500 RPM. Faulty oil
pressure gauge should not be overlooked as possible source if low pressure reading is encountered. Harley-Davidson® warning light comes on at
approximately 3 PSI, and is fairly reliable. Light may flicker at low RPM, but should quickly go out with slight increase in engine speed.
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Sudden clatter in previously quiet hydraulic lifter may indicate lifter failure OR excessively low oil pressure and should be investigated. It is not unusual
for hydraulic lifters to clatter when a new or recently rebuilt engine is first started, but noise should disappear as lifters pump up. Time required depends
on several factors including brand of lifter, oil viscosity, and temperature.
Models with oil tank below transmission require precautions to prevent air from entering oil pump during oil changes if custom cover
#31-6060/6063 is used or if bottom oil supply fitting location (hole #4) is utilized on universal cover #31-6061. If oil lines are rubber,
supply line from tank should be clamped during oil changes on these models, and clamp removed after tank has been refilled. If it is not
possible to clamp lines, oil circulation must be confirmed after each oil change. It is not necessary to observe these cautions if holes 5 and
6 are used for models with oil tank below transmission.
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Increased oil volume generated by S&S® pump may overwhelm stock scavenging system in knucklehead top end. If oil return becomes a problem, it can
be corrected by metering oil supply to heads. Oil fitting for top end supply line can be filled with solder and hole drilled in solder for this purpose. S&S has
performed tests and has successfully operated engines including panhead and shovelhead with metering holes as small as .060". Some knucklehead
owners have installed S&S carb main jet in cam cover top end oil supply fitting for same purpose, and adjusted oil flow with different size jets.
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For same reason noted above, stock knucklehead 5:1 ratio drive gears (25:5) may be preferable to 4:1 gears (24:6) used in later engines. In aftermarket
knucklehead engines that utilize later 1958-'81 style tapered pinion shaft in place of splined knucklehead pinion shaft, 1954-1972 style pinion oil pump
drive gear (HD #26349-54) may be used if corresponding 25-tooth gear is used on oil pump drive shaft. Correct 5:1 oil pump drive gears are available
through V-Twin Manufacturing. Contact local dealer for retail purchase.
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Paper gaskets are supplied as standard with each kit. S&S recommends paper gaskets but can provide mylar gaskets for 1936 to 1991 engines if desired.
Tests indicate that paper gaskets account For additional 2-3 PSI of oil pressure.
NOTE – All S&S and some H-D® crankcases have provision in rear of cam-side crankcase for three pipe-thread fittings. Hole #1 is for vent line from oil
tank. Hole #2 is used to scavenge oil from primary housing in models that circulate engine oil through primary housing (typically 1965-1984). Hole #
3 is used as crankcase breather on 1992-earlier models and on S&S engines set up for crankcase breathing or combination crankcase-cylinder head
breathing. Engine must have 1992-earlier style cam cover for crankcase breathing; otherwise, large oil losses will occur out Hole #3. Hole #1 will be used
in all applications. Hole #2 will be used in applications which lubricate primary chain with circulating engine oil. Hole #3 will be used in most “crankcase
breather” applications, excluding knucklehead and 1948-’64 panhead engines which utilize stock breather stud. Any hole not used (usually Hole #2,
occasionally Hole #3) must be blocked with supplied pipe plugs.
CAUTION