440 runs like crap with vacuum advance attached at idle. over 25” of vacuum at idle.

[Jc cooper]

With all the go info here that’s been given! One small thing to ck , is the throttle cable , at the clamp! Turn idle adjustment, all way off , loosen cable clamp and adjust accordingly! In correct, idle at or around 800 rpms! If a carb change recently! Maybe this could help problem!

 

[Don Frelier]

Yea sir it will run at that RPM. Gonna try that, hopefully that closes the throttle plate and It has zero vacuum then

OK but when you press the throttle and it gets to where the throttle plate is now it's almost assuredly going to do the same thing it does now?
Something is causing this.
I can run nearly 30 Degrees BTDC in my Charger at idle (and it's pretty happy there)

 

[diesel_lv]

OK but when you press the throttle and it gets to where the throttle plate is now it's almost assuredly going to do the same thing it does now?
Something is causing this.
I can run nearly 30 Degrees BTDC in my Charger at idle (and it's pretty happy there)

You are missing his point. He is pulling vacuum from both ports at idle causing the vacuum advance to add even more timing at idle than desired. Running 30° at idle is not the problem. He needs to adjust carburetor so no vacuum from ported port at idle. Then adjust the vacuum pot on distributor.

 

[Don Frelier]

You are missing his point. He is pulling vacuum from both ports at idle causing the vacuum advance to add even more timing at idle than desired. Running 30° at idle is not the problem. He needs to adjust carburetor so no vacuum from ported port at idle. Then adjust the vacuum pot on distributor.

My point is that if he has say a 17 degree arm for vacuum advance and he's at 10 initial then even with full vacuum advance he would be around 27 degrees at idle now.
Why does it run like crap? I don't think it should.
Yes, I would lower the idle speed but I think there is something else wrong.

 

[threewood]

You sure your throttle plate is closing at idle, as that "pink" port on the Edelbrock is ported vacuum..

Agree. Plate is open too far. What's your idle rpm? If it is around 700 to 900 rpm, add some advance to the distributor and back off the idle adjustment screw to keep it in that rpm range. Keep going until your pink port is zero vacuum. This will also change your total advance to put a timing light on it. Total should be close to 37 degrees.

 

[pedal2themetal]

HI 1,000 RPM's at idle is too MUCH That's why high vacuum on the ported port.... he said he can get it down to 800 or less .. He needs to get the rpm down to a normal level to get the no vacuum at the ported port.. which IS THE RED ONE circled.. you can see by looking at the two ports that the one above the throttle plates is the one on the left or red circle and that is the ported port (timed) for timing.
good luck
tim

 

[AMX364]

OP posted getting 30 inches at idle, not possible. It can get 30 degrees of timing. Use vacuum gauge for vacuum and timing light for setting timing. Stock 440 could get as high as 21 inches vacuum at idle. Cam change will be much less available. Vacuum pump can pull 30 inches on AC system, and no higher.

 

[Mr. Mike]

Back out the idle adjuster screw until there's a gap between the end and the arm on the butterfly shaft. Turn the screw in until it touches the arm then half a turn more.
With both ports plugged smooth out the idle with the mixture screws. Connect the distributor to ported vacuum and set the timing.
Apologies if this was mentioned before.

 

[383man]

You definetly have a bad vacuum gauge or its way of calibration. As many said there is no way even a stock 440 can pull 30" of Vacuum. Most idle around 16" to 19" in all stock form. The vacuum may hit close to 22 to 24 on a hard decel where eng vacuum will be the highest. As said see if you can turn the idle down to get the right port to not have vacuum until you step on the gas. Or you need to make some timing advance changes if you want to run vacuum advance at idle. Ron