The Edelbrock #50459 E-Street cylinder 290 Oval Port head is designed for Big-Block applications. The Edelbrock E-Street cylinder head offers American made quality and affordable performance. E-Street cylinder head features as-cast ports and are designed for entry-level street performance applications operating in the idle-to-5500 rpm range. The modern combustion chamber designs improve the combustion process and larger than stock intake and exhaust ports move more air through your engine for improve efficiency. For use on pre-pollution controlled vehicles only.