S&S Cycle 640 Camshaft for 1984-1999 Harley-Davidson Big Twins
The S&S 640 camshaft is engineered for extreme Big Twin builds, combining a high-lift profile with a lower TDC lift that makes installation more manageable without sacrificing top-end potential. Riders in large-displacement performance motors experience the aggressive power delivery and high cylinder pressure that only a cam designed for their level of commitment can provide.
Key Features
- High-lift cam for large-displacement and high-compression Big Twin engines
- Less valve overlap and fast ramps for increased cylinder pressure
- Lower TDC lift for easier installation than other high-lift designs
- Designed for hydraulic tappets
- Requires high-lift valve springs
- Made in the USA
Technical Specifications
- Lift: .640″
- Primary Compatibility: 110ci and above at 10.5:1 to 11.5:1 compression
- Extended Compatibility: 96ci-107ci at 11:1 to 12:1 compression
- Tappet Type: Hydraulic
- Spring Requirement: High-lift springs required
- Installation Feature: Lower TDC lift for easier cam installation
Fitment Notes
- Fits 1984-1999 Harley-Davidson Big Twin models
- For large-displacement engines (110ci+) at 10.5:1-11.5:1 compression
- Also fits 96ci-107ci engines at 11:1-12:1 compression
- Requires high-lift valve springs
- Installer must verify coil bind, valve-to-valve clearance, valve-to-piston clearance, and cam lobe-to-case clearance
- Review the Fitment tab for complete year and model breakdown
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