Dart big block Chevy manifolds are available with rectangular or oval ports to match your big block cylinder heads. These single-plane, high-rise intakes are designed to produce maximum power at higher rpm. Dart manifolds are designed to make engine building easier. For example, Dart's tall-deck big-block manifolds use standard length distributors. Carburetor pads are specifically designed for 4150 & 4500 carbs. Extended runner dividers equalize port length and are radiused to equalize cylinder-to cylinder fuel distribution. Optimized runner cross-sectional area maintains high mixture velocity for maximum torque. Angled runners turn the airfuel mixture smoothly from carburetor to ports. Dual distributor hold-downs simplify timing adjustments. Raised water cross-over and air gap insulate the intake charge from engine heat. Integral bosses for nitrous injectors.