I found this too, but it didnt post right. The last number in the chart are the CC,s but only go up to 81. Gives you a idea anyway.
[SIZE=+1]Cylinder Head Castings[/SIZE]
[SIZE=-1]Numerous cylinder heads are available for the AMC six. All utilize the same bolt pattern from 1965 to present Jeep 4.0L heads. Heads from 1964 to 1981 and all 4.0L heads use a 1/2" diameter head bolt, while heads from 1982 to 1988 for the 258 use 7/16" diameter head bolts. Heads manufactured during a given model year were used on all engines of that model year; there is no difference therefore between 1975 232 and 258 heads, for example. Valve head size and stem diameter are the same for all heads except the 4.0L which uses a larger valve head and smaller stem diameter. Rocker arm configurations vary from year to year, but the majority of heads use a non-adjustable bridged pivot design with stamped steel 1.6:1 rocker arms. Some older heads utilize a shaft mounted rocker arm system with ductile iron 1.5:1 rocker arms. Port sizes vary; older heads are typically considered “large port” heads, while newer heads are considered “small port”. The 4.0L head utilizes a revised port design of larger intake port cross section than the small port heads but comparable exhaust port cross section. The 4.0L head also utilizes raised intake and exhaust port locations for increased flow.[/SIZE]
[SIZE=-1]Large port heads were definitely used from 1965 to 1970, although there are rumors that they may have been used up to 1974. This is very unlikely due to the fact that AMC spent thousands on flow development of the newer small port design introduced in 1971. All large port heads I have found utilize shaft mounted rocker arms with an oil passage in the head that transfers oil from the camshaft bearing oil supply to the rocker shaft. Severe scoring and wear between the shaft and rockers is a common occurrence with this arrangement, and although there are multiple proposed solutions to the problem, none will result in the reliability and longevity required for serious performance applications, except a complete replacement of the system with a custom roller rocker arm arrangement. Large port heads feature semi-closed or fully open chambers, depending on the model year.[/SIZE]
[SIZE=-1]Small port heads were used from 1971 until the end of AMC production. The small port heads utilize very small exhaust ports with a substantially higher floor than the large port heads. Small port heads use either a small, open combustion chamber design or a larger, semi-closed chamber depending on the model year.[/SIZE]
MODEL YEAR ENGINE CASTING ROCKERS PORTS CHAMBER CC’S
1964-67 199/232 317071 SHAFT LARGE SEMI-CLOSED 56
1968-70 199/232 318988 SHAFT LARGE OPEN 62
1971 232/258 3211040 ????? SMALL OPEN 62
1972 232/258 3213809 ????? SMALL OPEN 62
1973 232/258 3213809 ????? SMALL OPEN 62
1974 232/258 3213809 ????? SMALL OPEN 62
3222652 ????? SMALL OPEN 62
1975-76 232/258 3224490 STUD SMALL OPEN 62
3224491 STUD SMALL OPEN 62
1977 232/258 3217259 STUD SMALL ???? ??
1978 232/258 ??????? STUD SMALL ???? ??
1979 232/258 3227258 STUD SMALL SEMI-CLOSED 74
1980 232/258 ??????? STUD SMALL SEMI-CLOSED 74
1981 232/258 ??????? STUD SMALL SEMI-CLOSED 74
[SIZE=-1]Note: Casting numbers are based on the NHRA list of approved castings, and thus correspond to model year. It is possible for a particular casting to have been installed on a model year vehicle up to one year previous or one year after those listed in the table, depending on the actual date of the casting and AMC’s remaining stock of previous years heads during the assembly of the vehicle. Combustion chamber cc's for 317071, 318988, and 3227258 were measured from heads in my posession. All other volumes are from outside sources.[/SIZE]
