My ’64 Valiant 225 / 904 has developed a vibration. I noticed it shortly after adjusting the valves (Stock solid lifter cam - 0.010, 0.020). It is very noticeable at low engine speed where it causes the engine to visibly shake at in park or in drive. I can feel a vibration while driving, also, but can’t be sure it’s the same thing. The valves themselves are not noisy. Using a rod/stethoscope I can hear a light knocking at about the same frequency and phase at the fuel pump, but nothing like it anywhere on the block or head.
Ideas?

might be a long shot but... check your timing maybe? I know my /6 shakes a bit if the timing is off, especially when idling.

I checked timing right before posting (Great minds think alike!) - 8 Degress BTDC. But it does feel something like it did when I had a bad plug wire a while back. I'm getting juice to all 6 plugs, checked by putting the timing light pickup on each wire. These are new plugs (gapped 0.040, old Accel SuperStock coil) and wires.
By the way, the vibration happens hot or cold.

Does the mis-fire go away if you plug the PCV valve?
It could be that a valve has tightened-up, you may want to recheck the valve lash, go a little looser on the exhaust valves to see if that helps.
DD

I finally got a chance to tinker on the slant. The vibration remains, and I'm running out of ideas.
You can count the cycles, and watch the motor shake, nice and steady. The engine actually feels strong (for a one-barrel stocker) when driving. It just shakes a lot.
Closing off the PCV made no difference.
The valves were pretty much as we had set them. I loosened the exhaust valves a little, but that didn't change anything.
Compression test showed less than 15 psi spread.
Spark tester shows juice to all six.
Spark plugs look good - about two weeks old.
Wires are also new.
Timing: 8 BTDC
Fresh motor mounts.
(225 / 904, Carter BBS, points)
Guess I'll check the trans mount, but I had it out not that long back and though it looked OK.
Any thoughts?

Points? Ack....

The points are going away! I promise! lol