Is it easy to tell the difference between a 302 and a 289

[FIA-ERA]

Plus, If the motor still has the original harmonic balancer it will give it away. The 289 had 3 bolt lower pulley while the 302 had 4 bolt lower pulley. If the block or heads have part# on them that will give it away too. The block should have a full casting part# above the starter looking up from under the car. If it's a 289 it should say C5AE or C4AE or at least start off with "C" as the dictates parts made in the sixties. If the block has "D", "E", etc that means it was made in the 70's then 80's etc. Other than that, as mentioned they are externally the same size. The Heads might have more "smog" holes and if it's a Mexican Block, it will have a good size casting "knob" on the front drivers side of the block. As mentioned, they converted over to 302's late 1967 and most 68 motors had 302 cast on them but some slipped out I'm sure. Regards, Matt