(1 customer review)


Speed And Science Big Bore (3-5/8″) CNC Billet Aluminum Bare Headset for the Harley-Davidson™ Shovelhead models


In stock (can be backordered)


  • Speed And Science ® designed Big Bore (3-5/8″) Billet Aluminum (6061-T6) Heads for the Harley-Davidson™ Shovelhead models.
  • This is a bare, “builder’s” kit. Requires separate purchase of Speed And Science intake manifold (available here) as well as valvetrain (optionally available here).
  • Designed to match S&S™ Sidewinder series pistons (P/N 106-5535,  not supplied).
  • This system achieves very strong torque curve and very respectable HP that peaks exactly where needed. This makes a superb street engine that will keep going strong for a long time, not just a 1/4 Mile!! We went to great lengths to make sure that our product is user-friendly and easy to service down the road also. No custom pistons, valves, guides, fasteners, etc. to worry about. Nobody offers that – there’s no hidden cost with our product!!!
  • Fast, very efficient ports designed to make peak power/torque within the useful RPM range. This is where a lot of people get confused. Please remember, the right balance between flow and velocity makes a good port. We could’ve made ANY shape ports and get HUGE flow numbers, but have made it RIGHT instead. As a result, your bike will pull hard from the get-go all the way up to the redline. The longevity and fuel mileage won’t suffer either.
  • 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. Threaded holes (M10x1) for Compression Release valves included.
  • Increased cooling area drops the head’s operating temperature up to 35F.
  • We have completely redesigned the Intake <–> Head interface, thus eliminating vacuum leaks.
  • Exhaust interface accepts both OEM single-bolt flanges as well as STD’s 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 )

Additional information

Weight22 lbs
Dimensions22 × 12 × 6 in

1 review for BIG BORE HEADS SHOVELHEAD, bare

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  1. Gerry (verified owner)

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