DISCLAIMER: *** Due to the hi-power output and certain mechanical features, this headset is to be installed/tuned ONLY by an experienced engine builder. Bike to be ONLY used on a closed course. Limited Warranty applies. ***
- Shovelhead Ported Heads by Speed And Science ®. This is the MIT version of the Big Bore (3-5/8″) Billet Aluminum (6061-T6) Heads/Intake system for the Harley-Davidson™ Shovelhead models.
- Bolt-on installation for all ’66-’84 models equipped with 3-5/8″ Bore cylinders. Designed to match S&S™ Sidewinder series pistons (P/N 106-5535, not supplied).
- This headset has been designed to make POWER, but our product is still user-friendly and easy to service down the road also. No custom pistons, valves, guides, fasteners, etc. to worry about.
- Proprietary, super-fast design of the combustion chamber yields 10.05:1 w. 4-1/4″ stroke (10.55:1 w. 4-1/2″ and 10.80:1 w. 4-5/8″ stroke) calculated compression ratio with Sidewinder pistons. Works well on the hi-octane (e.g. North American 94) pump gas. Compression releases included for easy starting.
- Valvetrain (AV&V and KPMI) components accept up to .625” valve lift, with almost .200” lift before valve-to-valve contact. Using tall camshafts may require an additional machining to provide necessary clearances.
- Increased cooling area drops the head’s operating temperature up to 35F.
- Single (Y-Split) CNC Billet Aluminum Intake Manifold (seals included) interfaces with Super G, PSI Big AIR, etc. We have completely redesigned the Intake <–> Head interface via proper EVO seals to eliminate vacuum leaks.
- Exhaust interface accepts both OEM single-bolt flanges as well as the aftermarket three-bolt pattern.
- Hi-tensile steel thread inserts (headbolts, intake, exhaust) installed; all original thread sizes, no need for “special” fasteners.
- OEM oil drain location.
- ***The difference in surface finish between the Intake (coarser) and Exhaust (smoother) ports is intentional.
- Warranty details and conditions are listed in the Installation Manuals ( Manuals download page )