JET Performance now offers a Quadrajet carburetor tuned for Chevy and GMC cars and trucks with 396 ci and larger modified big block engines. The carburetor is extensively reworked by increasing main well size and is balanced to assure top end high RPM fuel flow. Several circuit modifications are made to keep the fuel curve correct throughout the entire RPM range and to keep consistent idle quality. Includes a .149 needle and seat to ensure adequate fuel flow. The carburetor is designed for modified big block motors with a dual plane intake manifold, headers, 8.5-9.5:1 compression ratio and mild ported or aftermarket heads. Recommended cam specs: Duration at .050 min 210 degrees, max 240 degrees and a lobe separation angle of 110-114 degrees. Available as a complete unit or JET can rebuild your existing core.