Hey Eric,

My experience with timing on a '64 is that the factory mark works great, but I'm not an expert by any means.

As mentioned, the #3 clip position is the standard AFAIK, so I expect you'll see quite a difference changing that. You might also want to check the spec for the air screw when setting your idle (is it 1 1/8 turns out?).

If this next round of carb cleaning doesn't work, you might try a couple cap fulls of Sea-Foam in your next gas tank.

Good luck!

Dan