Offenhauser small block 4 barrel intake 66 and up
Brad,
here are some pics that might help you verify which manifold (64-5 or 66 up) you have. On the right, the more angled one (as compared to mating surface) is an early manifold. Both early and late have the angled pad, but early is twice the angle as compared to late. The hole size is not conclusive in that all intake bolt holes are over sized for the bolt. Often the 3/8 (later) bolt will physically got into the hole in an early manifold without interference especially on aftermarket aluminum manifolds.
Brad,
here are some pics that might help you verify which manifold (64-5 or 66 up) you have. On the right, the more angled one (as compared to mating surface) is an early manifold. Both early and late have the angled pad, but early is twice the angle as compared to late. The hole size is not conclusive in that all intake bolt holes are over sized for the bolt. Often the 3/8 (later) bolt will physically got into the hole in an early manifold without interference especially on aftermarket aluminum manifolds.
