These replica cast cylinder heads are made in the USA by STD. Their cylinder heads for Panheads always have been very popular because of their high quality and excellent performance. All cylinder heads are precision cast at 48,000lb tensile strength from 355 aluminum alloy and come with the seats installed. They feature ported intake and exhaust, Hemi-style combustion chamber, stock diameter valve seats and 1 9/16" O-ring style intake. Heads for 1955 thru 1962 models use the stock internal oiling system, whereas the heads for 1963 thru 1965 Panheads feature the stock external oiling system. All sets are available for use with 3 1/2" stock bore cylinders, as well as for use with 3 5/8" Big Bore cylinders. Both stock and Big Bore cylinder heads take the 1.950" diameter Shovelhead intake valves and stock size Panhead exhaust valves. Valves, valve guides, valve springs, rocker arms and rocker box covers must be ordered separately. All heads come in a raw cast finish.