JK 400 CFM Big Block Chevy Cylinder Heads with as cast ports. (Price per pair BARE) Upgrade:Select Option Available with CHE Ductile Iron

Available with CHE Ductile Iron Valve Seats or CHE Bronze Valve Seats

0" of area at the plenum and of the runner

Choose this option if you would like to have a 2 piece version of the BA LS or BA SB Ford intake manifolds

CNC intake and exhaust ports with CNC chambers

Available for all our shaft mount cylinder heads

JK 400 CFM Big Block Chevy Cylinder Heads with as cast ports. (Price per pair BARE) Upgrade:Select Option Available with CHE Ductile IronPRODUCT DESCRIPTION The CID JK400 Big Block Chevy Cylinder Heads flow an impressive 400CFM from as cast ports on a standard bore! This allows us to offer serious performance from an affordable cylinder head and intake package. These symmetrical port BB Chevy cylinder heads no longer have left and right unequal length runners. We straightened up the valve angles to move away from the factory bath tub chambers and to a smaller more efficient combustion