1967-9

Heads have small combustion chambers, 68 cc, for the best compression Buick big block heads. The 67 430 heads have casting numbers 1382983, 1382985 and 1372963. These 67 heads are known as big port heads. Some 1968 heads with casting number 1384720 are big port heads.

1970

Heads have good compression, 68 cc. First year to use the large Stage 1 valves. Heads have casting number 1231786.

1971-4

Heads have slightly less compression than previous years, 71 cc. Heads have year cast onto exhaust port at #1 or #8 cylinder. 1973-4 heads have casting number 1241860.

1975-6

Heads have open chambers and low compression, 78 cc. If earlier model heads are to be used on these blocks special head gaskets are required since water ports are not the same as earlier years. Earlier years are round while later ones are oval.

Example of water port differences will be shown below in a few weeks.