I have an 85 Camaro with a fresh crate 305. Everything on the motor has been replaced (distributor, plugs, wire, wire harness, fuel pump, etc) and the carburetor has been rebuilt.
It idles pretty good (could be better). But when coming off idle it stumbles a little. Also feels like it doesn't have a lot of power (I understand it's a weak 305). I've adjusted the secondaries on carb to assure they are at the right tension. Rechecked the float height and idle adjustments. Nothing seems to fix the stumble.
I've checked the timing and tried advancing then retarding it from 6 degrees didn't change anything (it's currently at 6 degrees).

 

Try advancing the timing more than 6.

Also, is the accel pump working? Correctly?

 

Its pumping fuel when depressed. Not sure if it's the right amount. I've tried having the choke plate closed some and fully open to see if the extra fuel from them being closed helped. Again didn't change anything.
When I plug the 4 wire from the distributor in it advances beyond the timing marks. Nothing changes with it plugged or unplugged.

 

Plugging in the 4 wire after setting base timing will do that. I'd still advance it more. Do you know that your harmonic damper outer ring hasn't slipped? These engines "like" way more timing than the spec. WAY more.

 

The harmonic balancer is new.

I went from 6 to 10 degrees. Maybe a little improvement but certainly not how it should be.

 

Well, you got some improvement...try more? Until it peaks out and goes the other way.

I'd check for vacuum leaks proper accel pump action. Also check for spark leaks from bad wires. I know they're new.

 

what is the dwell for the MCS doing?

 

I don't have a dwell meter. Current settings are 3.5 turns out on idle screws. I tried going to 1.5 turns and it drove the same so I put it back at 3.5.

 

If you have a DMM with a Hertz/Duty Cycle range (many do) you can do the same as a dwell meter. You're looking for around a 50% average setting, a.k.a., 30° on a dwell meter in a 6-cylinder configuration.