. Its advanced runner design eliminates the need for extensive porting to achieve maximum performance. The "long" and "short" intake ports are relocated to equalize runner volumes to within one percent. The minimum wall thickness of .450" allows major modifications without welding. The D-shaped exhaust runners have a port volume of 145cc's. The Super Duty head's intake valve angle is 18º , and the exhaust valve angle is 9º. This represents an 8º "roll" compared to a production big-block V8 head. The ductile iron seats installed in the 91cc combustion chambers will accept 2.40" diameter intake valves and 1.90" exhaust valves. The Pontiac Super Duty head uses 3/4" reach gasketed plugs. It is cast iron from A-356.2 alloy aluminum." Above Added: Thu September 8, 2016, 4:14 pm EST
NEW GM BIG BLOCK CHEVY HEADS MADE BY Pontiac. BIG CHIEF HEADS OR # 10045427. HEADS HAVE spread ports AND 18 degree intake valve . HEADS HAVE BEEN PROFESSIONALLY PORTED AND FITTED WITH WATER OUTLETS.
THE ULTIMATE BIG BLOCK CHEVY HEADS. HEADS ARE FRESH OUT OF STORAGE. LAST OWNER WAS BUILDING A 540 CID BBC WITH A .950 LIFT ROLLER CAMSHAFT.
HEADS COME WITH NEW MANLEY TITANIUM VALVES, AND GM BIG CHIEF VALVE COVERS. HEADS BOLT ON TO ANY BIG BLOCK CHEVROLET AND MAKE UNREAL POWER OUTPUT.
FROM THE PONTIAC PERFORMANCE BOOK:
"Pontiac Motorsports' aluminum cylinder heads for big-block V8s have high-flow 460cc intake runners which are raised and relocated to enhance airflow. This head is designed for Pro Stock and similar all-out racing engines which range in displacement from 450 to 600 cubic inches. Its advanced runner design Above Added: Thu September 8, 2016, 4:12 pm EST