S&S Special Application (SA) B1 heads are intended for racing and radical street applications with high cfm requirements. For maximum versatility, SA B1 heads are available in three stages of completion: unfinished, semifinished, and fully machined. Due to the complex machining required to complete unfinished and semi-finished heads, we recommend them only for professional engine builders with extensive machining capabilities. Fully machined SA B1 heads require some finishing and final assembly. All SA B1 heads, regardless of part number or options, are shipped unassembled. This allows the builder to finish them exactly as required.
- Available for modified Harley-Davidson® Evolution® big twin engines and 1986'03 Sportster® models
- For engines with a minimum cylinder bore of 4", and will accommodate cylinder bores up to 4 1?2"
Features and Benefits
- CNC machined and cast from 356 aluminum alloy and heat treated to T6 specificationsmaximum structural integrity and heat dissipation
- Head bolt circles of 5.675" with 1?2" head bolts or 5.750" with 7/16" head bolts can be used (S&S can match the industry's more common bolt patterns if requested or other patterns can be machined if a print is provided)
- Head gasket surface has sufficient material for machiningadjust compression ratio without compromising structural integrity
- Internal or external oil return passages are provided on fully machined SA heads
- Intake port utilizes a directional vane that routes the incoming fuel-air mixture around the valve stem and guideminimizes turbulence and improve flow and cylinder fill
- With minimal finish porting of a fully machined SA head, intake flow is typically 195 cfm at 10" water and 0.700" lift
- Intake port is located approx. .500" higher than stockmay cause interference problems with the top motor mount, particularly in rubber-mount chassis
- SA intake port requires the use of a special intake manifold and mounting hardware (not includedmust purchase separately). This manifold will be machined to customer specificated manifold length and bore size. Port-to-port measurements must be supplied from mock-up or assembled engines. Click here for ordering S&S manifolds/measuring info.
- Professional porting is recommended in order to achieve the full potential of these heads
- Exhaust Port has also been relocated in SA heads, requiring that a special exhaust system be fabricated
- Typical exhaust flow with minimal finish porting is 147 cfm at 10" water
- Typical intake flow is 200cfm .700" valve lift
- The valves, seats, and guides used in SA heads are compatible with exotic fuels and are designed to withstand the high valve spring pressures required for high rpm operation.
- Standard SA intake valve diameter is 2.100". Standard exhaust valve size is 1.750"
- Both cast iron and bronze valve guides are available. Cast guides are recommended for moderate duty and where longevity is a consideration. Bronze guides can accommodate higher lifts and are recommended for severe duty applications where longevity is not a primary concern.
- Combustion chamber in completely machined SA heads is similar to the closed, high-quench chamber used in 3 1?2" and 3 5?8" bore Super Stock® heads. SA squish shelves are rounded to improve combustion chamber dynamics in large displacement, high-revving engines. Heads may also be purchased with the combustion chambers unmachined.
Kit contains completely machined front and rear cylinder heads with valve seats and guides installed, and additional parts which are not installed include: valves, seals, manifold mounting hardware, and exhaust flanges.Valve springs are available separately. Manifolds must be purchased separately.NOTE:
SA cylinder heads add approximately .300" to engine height (compared to stock heads), causing interference problems in some chassis.
Pushrods for engines with S&S SA cylinder heads must be .200" taller than they would be with stock heads, but the pushrod cover keepers will be the same length as with stock heads.
Flow figures are based on measurements obtained with a SuperFlow® 600 flow bench at the S&S Research and Development facility in Viola, WI.MACHING OPTIONS:
Includes completely machined front and rear heads with valve seats and guides installed. Also includes valves and seals, valve springs, collars, and keepers.Semi-Finished
Includes front and rear cylinder heads with finish machining on rocker cover gasket surfaces, front motor mounts for use in Harley-Davidson® Sportster® models, and manifold mounting bosses. Valve guide holes and valve spring pockets are sized. Valve spring pads, intake and exhaust ports, and head gasket surfaces are "cleaned up" to provide the machinist with a reference point. All other machine work is left to the customer. Head bolt holes, pushrod cover counterbores, spark plug holes, oil return passages, and combustion chambers are not machined. Valves, valve guides, seats, and seals are included but not installed.Unfinished
Includes front and rear cylinder heads with rocker cover gasket surfaces finished to provide the machinist with a reference point. All other machine work is left to the customer. No valves, valve guides, or other hardware is included.