S&S Cycle Sidewinder 3 5/8 Big Bore Cylinders for 1936–1999 Big Twins - Manual (Page 7)

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C. Disassemble crankcases and bolt front and rear cylinders to drive side crankcase half.
D. Drill through oil return hole in cylinder spigots into crankcase approximately 5⁄16" deep to connect with holes previously drilled using 1⁄4"
diameter taper length drill.
E. Unbolt cylinders and remove from crankcase. Use file to break thin web of material at gasket surface. File slots to width of drilled holes.
Crankcases 1984 to 1999
NOTE: Oil return passageways in Sidewinder® cylinders for Harley-Davidson® Evolution® engines are moved out slightly as compared with stock oil return
holes to accommodate 35⁄8" bore. This creates misalignment between cylinder oil return passage and crankcase oil return passage.
To modify cases and return oil properly, perform following steps:
A. Place cylinder base gasket on cases and note amount and direction of return hole mismatch.
B. Chamfer edge of hole accordingly at minimum of 45˚ angle to insure adequate flow.
7. Crankcase and Piston Skirt Clearancing (All)
Crankpin Nut Clearance
Bosses on inside of cam side crankcase half must be clearanced for crankpin nut. See Picture 2.
NOTE: Crankpin nut will usually clear on cases of 80" shovelhead and Harley-Davidson® Evolution® engines when 41⁄4" or 43⁄8" stroke is used. When stroke
41⁄2" or longer is used, nut will usually hit. S&S® recommends all cases be checked no matter what stroke is used. S&S Crankpin Nut Clearancing
Gauge, Part #53-0005, for cases 1958 and later, and Part #53-0009 for cases 1957 and earlier are designed to mark crankcase that allows sufficient
crankpin nut clearance for specific stroke to be used.
Figure 1
Picture 2