EDELBROCK

Cylinder head specifications:, combustion chamber volume: 87 cc, intake runner volume: 215 cc, exhaust runner volume: 175 cc, intake valve diameter: 2.11 in., exhaust valve diameter: 1.66 in., valve stem diameter: 11/32 in., valve guides: manganese bronze, deck thickness: 5/8 in., valve spring diameter: 1.46 in., valve spring maximum lift: .575 in., rocker stud: 7/16 in., guideplate: hardended steel, pushrod diameter: 5/16 in., valve angle: 14 Deg., exhaust port location: stock ram air iv, spark plug fitment: 14 mmx 3/4 reach, gasket seat. These cylinder heads are designed for outstanding performance gains in 1962-79 389-455 c.i.d. Pontiac engines. They are patterned after the 1969-70 ram air iv pontiac cylinder head. Performer heads #60579/#60575 are 50-state emissions legal for 1965-79 vehicles. They feature 87 cc combustion chambers designed to maximize performance while using less expensive, low-octane fuel w/ a streetable 9.5:1 compression ratio. Our performer rpm heads w/ the 72 cc combustion chamber are for higher compression engines. Performer rpm #60509 is semi-machined & must be finished by a professional cylinder head porter. They include valve guides & seats installed w/ no intake pushrod holes. Performer rpm #60587 is not port matched or bowl blended & is NHRA accepted for stock & super stock. Deck thickness: 5/8 in., rocker stud diameter: 7/16 in., pushrod diameter: 5/16 in. (width of slot in guide plate).