Good torque and excellent mid-range power. Best with lower gear ratios. 1,000-5,200 RPM Operating Range 210/218 Duration at .050". 111 Degree Lobe Separation Angle 0.477"/0.493" Valve Lift Designed for use with common restrictive factory exhaust systems, including OEM exhaust manifolds. Improved throttle response and increased low and mid-range RPM horsepower for towing and off-road. Fits '64-'98 AMC 199-258/4.0L Made in USA