I've read a lot on this topic, but I'm still learning here's my question:

I have new a 440 with decent sized cam and a NEW sixpack set up. Car starts up quickly, runs at 180-185 degrees F and shuts off clean. Mechanically sounds like a beast.

CAMSHAFT: 241/247@.050" .540/.540 lift. (hyd.flat tappet)

I'm trying to get the center carb to idle "within the idle circuit" but I'm having a little trouble.

When I put a vacuum gauge on the "spark port" of center carb at idle, it's still pulling vacuum...so it seems I need to turn the idle adjustment screw out to close throttle blades more...but if I did this enough to get a zero reading on the gauge the engine would die as it cant idle at 600rpm.

I've advanced the timing to the point where I'm not sure I should go much more...about 22-24 degrees INITIAL at 850-900 rpm. I was hoping to stay about 12-15 initial.

I started the idle circuit screws (center carb,both sides) at 1.5 turns out and tried to turn them out a bit more and watched the vacuum gauge (this time on manifold vacuum) and the needle just moves around with the slight fluctuations of the idle. Basically, I'm not confident in the reading on the gauge with it moving around.

What should I be doing with the idle circuit screws? How should they effect idle? Is it too early to adjust them knowing I'm not running 100% off the idle circuit on the center carb?

I was hoping I wouldn't have to modify the throttle blades (drill holes in them etc) to get the car idle within the idle circuit, so I'm looking for answers.

Advice?

Thanks!