edelbrock carb tuning?

UGH!!! The neat thing about free advice is you get what you pay for. Lotsa BS in this thread!

Let's get back to first principles. There's an old saying that "99% of carb problems are ignition related". This old saying is based in historical fact. Anyhow, your situation begs a few questions:

Is this carb new, or used? Do you know it's history? Do you have the Edelbrock manual that came with the carb? Have you read it?

Are you sure you don't have a vacuum leak somewhere? 99% of all non-ignition related carb problems are vacuum leaks. PCV system installed and functioning correctly?

Is this off idle flat spot something you can "step through?" That is, if you push the pedal down a little further, say 1/2 way will the car accelerate smoothly? Or, the more you push the pedal, the more is will bog and blubber?

If the carb is new, did you double check the float levels? Even if it isn't, this is the absolute first thing you must do when tuning any carb.

Do you have a vacuum gauge? Timing light? Tachometer? Dwell gauge (for points)?

Is your distributor functioning properly? Does the mechanical advance work? Test this by turning the rotor clockwise by hand and releasing, it should spring back all the way. Vacuum advance? You need a hand vacuum pump to test this (pretty cheap at Sears or HF). It should move the breaker plate when vacuum is applied, and hold vacuum. If it springs back as soon as you quit pumping vacuum, it's junk, and will cause an off idle stumble. Alternately you can test one of two ways: With the engine running at idle, connect the vacuum advance hose to the manifold vacuum port (drivers side) on the front of the carb. The timing should advance 10-15 degrees and the idle speed should pick up noticeably. Alternatively, disconnect and cap both ports on the front of the carb and test drive the car. If the stumble is gone, the vac advance is leaking. If you have points, make sure the dwell is correct. Static point gap will get you close if the distributor is new, but dwell is the only way to set accurately. How about the other obvious stuff like plugs new and gapped correctly, cap, rotor and wires new?

How about general engine health? What is your manifold vacuum at idle? Is it steady? Does the needle twitch or fluctuate? Internal vacuum leaks? Test this by sealing the crankcase breather with your thumb with the engine at idle. You should feel vacuum build, but the idle speed should not change. If it does, or if pressure builds you have bigger issues.

Next, we can focus on tuning the carb. Read the carb manual, it tells you pretty much everything you need to know. Seriously. Next do what Prine said above. This will get you "lean best idle" but will probably end you up with the timing a bit fast. No big deal, you can always roll it back. The big thing when setting the carb is to get the timing set to something reasonable and then leave it alone so you can get the carb dialed in. So, go richer or leaner? On an out-of-the-box 1406 at sea level, I'd start by going richer. Assuming you have the stock #1427 (.098) main jet, try a #1455 (.073x.042) rod. That will be a 6% increase. Orange springs will probably help throttle response as well.

ONLY CHANGE ONE THING AT A TIME! And then test drive. If you change 2 or 3 things you may fix one problem while creating another. You'll never know where you're at or what worked.

As for the crank damper, if the ring has slipped not only will you have a hard time knowing where your timing actually is, it isn't doing any dampening anymore. Fix this.