Find CHEVROLET Cylinder Heads and get Free Shipping on Orders Over $99 at Summit Racing! JavaScript Disabled. PROMAXX Performance Freedom Series Small Block Chevy Cylinder Heads. Cylinder Head, Freedom, Aluminum, Assembled, 64 cc Chamber, 185 cc Intake Runner, Straight Plug, Chevy, Pair.
There are two casting marks with two humps - a tall one and a short one. Heads with the taller casting mark were produced in four casings. Casting numbers typically had seven digits, and heads were commonly recognized by the last three numbers.
![Sb Chevy Heads Sb Chevy Heads](/uploads/1/2/5/6/125617413/722322515.jpg)
Heads with tall casting marks were identified as 291-, 461-, 461X- and 462 castings and did not have accessory bolt holes. Intake/exhaust port volumes were about 170cc and 64cc and valve diameters were either 1.94 and 1.5 or 2.02 and 1.6 inches for the intake/exhaust. Combustion chambers were typically 62 to 64cc and provided higher compression ratios. These heads were found on Chevy high-horsepower 302, 327 and 350 CID engines, including the fuel-injected 327s, from which they got the nickname 'fuelie heads.' Double-hump heads were popular performance upgrades for engines that were not equipped with them and are in high demand today in racing applications where factory heads are required. These castings are also becoming more difficult to find for collector car enthusiasts who need factory-correct components with matching ID numbers. For performance applications, there are other GM castings that are similar in specs.
![Chevy Chevy](http://i.ebayimg.com/images/i/291183473392-0-1/s-l1000.jpg)
The '041' heads compare favorably but the '96 to '01 GM L-31 5.7L Vortec heads are in much greater supply, still available from GM and flow better than even the best double-hump heads.