Cleaned my carb out from the junk I found in the other thread and she's running beautifully at idle now! But there's another problem:

In Park or Neutral I can rev the stuff out of the engine in the Demon to even almost 4K and snap my foot off the pedal and the RPM plummets but settles at about 850RPM just fine. However, when I do the same in gear (either holding the brake or moving forward), the instant I take my foot off of the pedal the RPM plummets but either chokes the engine so it settles at approx. 250RPM or kills the engine outright. If the engine just chokes to 250RPM, it will pretty quickly go back up to 850 where it should be, but still this shouldn't be happening, methinks?

I have checked all gears and it's only when the engine has load from the transmission (904). I think it might have to do with the transmission, but something tells me I'm an idiot for thinking that. Any insight?

Increase initial timing or raise idle speed.

Maybe my problem is similar to yours. I have a 360 and 4 speed in my Duster, 292/508 cam, Victor 340 intake, block .030 over KB 8.66 comp pistons, '923 heads milled .020, NEW Holley 750 VS TTI headers and factory electronic ignition. Mine idles fair, (not bad for a lumpy cam) but will bog and stall for no reason. I can slip the clutch and put around, but when I lean into it, it also bogs and stalls. It is getting a healthy accelerator pump shot. In the past, I have found that when an engine stalls under a load , the problem usually lies in the ignition system. I had a slant sick in a 77 D 100 that did wouldn't go over 29 mph. I tried everything, THEN swapped in a known good used distributor cap and plug wires, and it was finally able to peel out and break the speed limit. I am going to try another set of plug wires in my Duster tomorrow. Good luck with your project!

By the way do you have the vacuum advance on manifold vacuum (by the throttle blades or off of the intake manifold) or ported vacuum?

check to make sure the rods and plunger are not sticking in the bores

after cleaning them in cleaners the alum get very dry

I use a little 3in1 oil on the plugers and make sure they move smooth in the bore up and down

you can pop them right out and back in

did you saok the carb or just spray it out?

its best to soak them in a good cleaner,I had the same stuff a couple yrs ago on the eddy and Q-jet

took a good 20 min soak and 150 psi blowdry to clean all the small passages

On the Edelbrock installation instructions, it says to put non-emission-control cars' vacuum advance into the manifold vacuum

Ignore the edelbrock instructions. The vacuum advance should be hooked to ported vacuum.

put it on ported vac side

set timing with light,set curb idle,adjust idle screws for highest vac reading

going back over each to fine tune it

mine idles 750-800 rpms in gear 850 curb idle,can stomp it from dead stop and not miss abeat with it up to 5000rpms

step up to the fram HP1 fuel filter or the like

Re-timing and checking my mixture didn't help. I went all the way from 18° initial to 24° initial in two-degree increments and didn't make a lick of difference. Also, the carb shows 15hg of vacuum, so it seems to be in good shape.

Other ideas?

I have to disagree with you guys, ported vacuum is wrong in theory and in my experience it is wrong in performance.

Manifold vacuum is vacuum under the throttle blades. As idle this vacuum is very high. At full throttle it is zero, or near zero.

Ported vacuum is the vacuum above the throttle blades. At idle it is zero and the more air that flows through the venturis the higher it gets. You can curve a dizzy to work with it, but why? Ported vacuum is part of emissions control because more advanced timing causes a dirtier exhaust charge. When you hook up to ported vacuum it causes your engine to run on whatever initial you set it at, lets say 8. The engine runs crappy on 8 degrees of initial. It will idle rough and have very poor response. Lets say theres 24 degrees of mechanical advance in the dizzy. When youre driving normally its just adding timing based on how much air is flowing through the carb, basically the rpm. At WOT at the top of the gear its adding timing, lets say 10 degrees. So you have 8 initial (not enough), plus 24 mechanical, plus the 10 from the ported vacuum. You now have 42 degrees of timing, which is too much and if it pings you have to retard it so the engine runs even crappier at idle, although it will smell cleaner. Also at high RPM the engine doesnt like timing as much, the extra timing will hold the engine back and make it not want to wind up.

Manifold vacuum basically works opposite. It will add the most timing at idle. Your 8 initial is increased 10 by the vacuum advance and you now have 18 initial. At WOT you will have your 8 initial plus 24 mechanical so you have 32. Crusing down the highway at light throttle the vacuum advance will add a few degrees in and give you better gas mileage and part throttle response as far as maintaining speed goes.

If you run ported vacuum you may as well just recurve the distributor to add in whatever advance the vacuum advance is adding in my eyes.

This is my veiw on the vacuum advance. Maybe I'm wrong, maybe there is no right answer. But I know it works better for me this way.

What engine is this and what cam? And do you have power brakes?