Instruction Manual

2
S&S® Gear Drive Camshaft Specications for Harley-Davidson Twin Cam 88® Engines
Cam
Name
Valve Timing Valve Duration
Valve
Lift
Centerline Lift @ TDC
Intake Exhaust Intake Exhaust Intake Exhaust Intake Exhaust
510G 20°/38° 52°/20° 238° 252° .510" 99° 106° .187" .179"
570G 20°/40° 55°/20° 240° 255° .570" 100° 107.5° .187" .179"
585G 20°/45° 60°/20° 245° 260° .585" 102.5° 110° .186" .179"
625G 20°/55° 60°/20° 255° 260° .625" 107.5° 110° .189" .184"
640G 25°/60° 65°/25° 265° 270° .640" 107.5° 110° .228" .214"
Chart 1
INTRODUCTION



 
 
 
 
 

COMPATABILITY NOTES:
S&S Cam Gear Drive is not compatible with camshafts designed for the stock style chain cam drive. S&S Cam Gear Drive must be used with S&S gear drive

style camshafts.
2006-Up gear driven camshafts kits 510G, 570G and 585G are compatible with stock 2006-Up valve springs. Due to the change in lift from the cams, new

pushrods are required during installation. S&S adjustable pushrod kit 93-5095 is recommended for engines with stock length cylinders. Longer pushrods
are available for engines with longer than stock cylinders. See the S&S Catalog for pushrods.
S&S camshaft installation Kit 33-5240 is strongly recommended when installing S&S cam gear drive. This kit includes hardware, gaskets and bearings

required for cam installation, this kit does not include oil pump o-rings.
All S&S gear drive cam shafts except for the 510G, 570G and 585G required that the stock valve springs be replaced with high lift spring
kits. Some high lift spring kits require clearance checks and many require cylinder head modications to prevent contact between top
color and valve seal, and to achieve correct installed height. See the instructions with your spring kit for exact specications.
When using S&S gear dive cam shafts with stock pistons, valve to piston clearance may need to be checked.
 See Chart 2.
CAUTION
Valve to Piston Clearance Chart Stock Harley-Davidson® Pistons*
Head
Style
Cam
510G 570G 585G 625G 640G
 OK OK OK OK 1
 OK OK OK 1 1
 2 2 2 2 2


 
 
If stock heads are decked, valve to piston clearance must be checked. If insucient clearance is found, valve pockets must be modied. 
When using S&S pistons with S&S heads which are unmodied or have been decked no more than .062”, no additional valve to piston clearancing will be 
required.
Chart 2