Your stock timing setting from the manufacture with an operating vacuum advance (but disconnected for setting) is like 8*-10*. So now with the advance can hooked up u have 41* advance that rough idle could be detonation. Try 10* initial timing and see how it idles?
Another item is that u have an automatic trans and sometimes (usually with a large cam) using ported vacuum helps prevent the engine from stalling and dying when the engine is loaded by the trans shifted form park to drive (or reverse). But we don't know what u have for a camshaft either.
But right now i read u have too much initial timing and this must also be very tough on your starter as it starts to fire while ing over.
To choose a vacuum can u will need to measure idle vacuum and vacuum at 'bout 3000rpm. This will give u full advance at idle and no vac adv at 3000rpm when set up right with the correct vac can.

Thats plenty for now,
cardo0

 

Vacuum is around 16 at idle. Smooth is a relative term...it is smooth compared to my in-laws 69 Camaro, but not so smooth compared to my Z06.
And yes, the avatar is my garage.
Carb was new when installed many years ago...I do not think it was a reman at the time. I was also thinking of just trying to borrow another carb to test...I just need to find one.
Yeah, the TDI is nice for the mileage, but certainly not a performance machine.
Cam specs:
Trick Flow Cam
Intake Duration at 050 inch Lift 212
Exhaust Duration at 050 inch Lift 216
The idle drops slightly when taking initial back to 10, but so does the performance, possible due to the mecahnical advance only adding about 16 degrees. The car starts right up, actually easier than it ever has (with timing set at 20 initial. I wouldn't say my idle is rough, it is just not as smooth as I would have thought. It is hard to describe how smooth the idle is...it is not stalling or shaking the teeth out of my head, but you can definitely feel it when it I am sitting at a stop light.

 

Connecting full vacuum to the advance unit will cause more advance at idle which in turn will raise the idle RPM. You will have to reset idle speed after making ANY adjustments to base timing and/or the vacuum unit. That's actually perfectly normal.

Full vacuum will produce a better idle due to advanced timing. Ported vacuum at idle is stricly for emissions controls.

With Vacuum advance disconnected 36 degrees fully advanced is the expected range. With the Vacuum advance hooked up normal advance is around 52-54 normal.

With the Edelbrock 1406 you will definitley want to start playing with jetting. If you are using the stock configuration of the 1406 it will be running far too lean. Don't mess with the secondaries I'm talking just the primary jets and rods. Pull out the manual and use it as a guide to change to one stage richer at a time.

 

Only 16* mechanical means the bushings on the stop pins are limiting the advance curve. For performance your going to need 36* full requires 26* mechanical if only using 10* initial. Show me where MSD says to use 20* initial timing for your street fire dizzy? U need to read up on setting the distributor. But if u want to use 20* initial is truly your own choice. Heck give MSD a call. And u should at least read this MSD w/s info:http://www.setyourtiming.com/Timing_...l#TimingCurves. MSD used to have plenty of timing curve examples on thier w/s but i don't see any that would help your situation - so give them a call as they should stay behind thier product.
But what i don't understand is how u use a paint mark for the 12* and now can read 20* initial advance. As i said before u need to very TDC and mark the balancer. I feel i can't give u the assistance u are looking for as its like shooting at a moving target over the internet.

That sounds like a good cam for the street but i don't see the full duration figures and the Lobe Separation Angle either to figure the overlap. A compression test would be nice to see want engine has for compression now - remove all the plugs and tie open the throttle plates, just turn it over and read the gauge (2 hour job). Your idle vacuum sounds OK but what is vacuum at 3000rpm? U need to nail your engine spec before u can nail the tune. Again i don't see how i can help u much here looking at different numbers each new post.

Good luck with the tune,
cardo0