The Edelbrock #5023 E-Street cylinder heads are designed for Ford 289-351 W V8 applications. The Edelbrock E-Street cylinder heads offer American made quality and affordable performance. E-Street cylinder heads feature 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.INSTALLATION NOTE: • Ideal for operating in the idle to 5500 rpm range • Use with hydraulic flat tappet camshafts, .550" maximum lift - not compatible with hydraulic roller camshafts • 289-302 with 7/16" head bolts require #9680 head bolt kit • 1.90" heads are ideal for stock pistons • Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat. • Requires hardened pushrods. 289-302 c.i.d. with 7/16" head bolts requires #9680 head bolt bushing kit.