Air Flow Research
AFR 180cc and 195cc SBC Eliminator Street Cylinder Head
AFR's new "Eliminator" SBC line raises the bar for 23 cylinder-head technology. Completely redesigned castings feature improved oil drain back, stronger rocker stud bosses, and revised cooling passages. A clean sheet of paper approach to port and combustion chamber designs has boosted efficiency levels dramatically with smaller cross-sectional areas flowing 5-10 percent more across the entire curve for increased airspeed. AFR is the first company to incorporate "Gen III" technology into their 23 product line by fitting them with 8mm valves, and lightweight springs and retainers (a 50-gram weight reduction per valve/spring/retainer assembly), which reduces valve float and improves high-rpm power and reliability.
The AFR Emissions Legal (versions from 1969 to 1994 with heat riser, CARB EO #D-250-2), 180cc intake port small-block Chevy cylinder heads are available in your choice of straight, or L98 angle plug versions. The 180cc heads feature a 74cc or 68cc combustion chamber with a 64cc exhaust port and a 3/4-inch thick head deck (ideal for nitrous or blower applications.) The 68cc chambers are designed for flat top or dished pistons; domed pistons will require additional machining. Standard valves are 2.020 intake and 1.600 exhaust with AFR's hardened ductile iron interlocking valve seats. The exceptional flow characteristics, ideal operating range of idle to 5500 rpm (higher rpm ranges possible depending on combination of parts), 23 valve angle, and standard valve spacing make this the perfect street head for 327 cid to 350 cid engines from 1955 to 1986. They're also available for 1987-to-present engines with center bolt valve covers and two center intake bolts at 72 angle. No special parts are required for these heads.
Sportsman II 200cc Iron SBC Cylinder Head
Continuously improved since its 1987 introduction, the Sportsman II is still the industry's most popular cast-iron high-performance head. Featuring RightCast 200cc intake runners, Fast-Burn chambers, and your choice of angled or straight plugs, they're good for 30-70hp increases right out of the box. They're the aftermarket's only 50-state emissions-legal, cast-iron, high-performance cylinder head (E.O. #D-343-1). World Products heads are precision CNC-machined, and indexed off the chambers to assure perfect alignment with the cylinder. They flow 238 x 134 @.600 as-cast.
Cost per pair: $645.98 (bare); $968.98 - $1101.98 (assembled).
S/R Torquer 170cc Iron SBC Cylinder Head
An improved replacement for the factory Chevrolet 327-350-400 cylinder heads, World's S/R Torquer series features 170cc intake runners, and can provide up to a 30hp increase over most OEM castings. Note, however, that these heads are accepted by many racing associations as "stock," and are 50-state emissions legal. S/R Torquer heads accept early and late model accessories. The exhaust valve seats are hardened to provide compatibility with unleaded gas. The S/R Torquer heads are available in 67cc and 76cc versions for engines up to 1986, and 76cc for 1987-and-later applications. They are designed to use 2.020-inch intake and 1.600-inch exhaust valves. They flow 206 x 116 @.600 as-cast, and work well in engines from 302 to 400 cid.
Cost per pair: $598.48 (bare); $883.48 (assembled).
Motown 220cc Cast-iron SBC Cylinder Head
Designed to provide an even greater intake charge than the Sportsman II, World's Motown 220 features the latest high-tech 64cc chambers and RightCast 220cc runners to provide a combination of excellent flow and high velocity. With high-flow ports (flow: 269 x 169 @.600 as-cast) and standard intake valves, Motown 220 heads are the ideal complement to large displacement small-blocks (383 cid and larger).
Cost per pair: $655.48 (bare); $1101.98 - $1291.98 (assembled; with your choice of straight or angle plug configurations).
Freedom 188cc Aluminum SBC Cylinder Head
Patriot Performance's new Freedom Series heads provide exceptional quality and great performance. The intake and exhaust runners on these heads were modeled after its CNC ported heads and flow 260 @ .600-inch using a 188cc intake runner. The combustion chamber volume on these heads will be 64cc, and castings will be available in straight or angle plug. The 188cc Freedom heads are designed for street/strip applications and are equipped with the following: 2.02/1.57 21-4N stainless steel valves, steel retainers, .575-inch lift springs, custom honed bronze guides, machined spring bases, viton rubber seals, 3/8-inch studs, and guide plates. A 220cc runner version and a BBC version will be coming soon. These heads will fit all '55-and-up GM 23 small-block engines (except LT1).
Cost per pair: $795.00 (assembled).