An excellent street, strip, oval track, truck or marine performance upgrade. Maximum torque and throttle response from idle to 6,000 RPM. Best for 327-400 cubic inch engines. Works with most standard components. Dart Iron Eagle 23° 180cc cylinder heads are an affordable alternative to more expensive Aluminum heads. These 180cc heads out perform many larger heads in a wide range of applications. Long wearing Bronze valve guides, screw-in studs, multi-angle intake seats and hardened and radiused exhaust seats are standard. Best of all, our precision cast ports produce outstanding airflow without time consuming porting.