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

67charger440 · Dec 21, 2021

Greetings- I have a mild 440 in a 66 charger. It has a edelbrock 1407 750 CFM carb. When the vacuum advance is attached, the motor stumbles and misses at idle. When I disconnect the VA, it runs MUCH smoother. So I bought a vacuum gauge. I get 25” from the pink pink port and 30” from the blue port… at idle. It’s advancing way too much at idle. Distributor is set at 10° initial. Engine is also running richer than bill gates. Yes I’ve used the vacuum gauge to zero in my idle mixture screws. What gives?

***update**
-Backed down idle to 700 at idle.
-got throttle plate to cover port
- engine still hates having the vacuum advance attached.
- stumbles upon delivery acceleration.

is there a way to adjust the travel Length of the VA canister? I got this distributor from Halifax distributors from this forum.

diesel_lv · Dec 21, 2021

It would appear both ports are manifold vacuum. That can be useful w an aggressive cam. If your engine idles smoothly with it disconnected, then you need to find a port that gives "ported" vacuum (no vacuum) when at idle to the distributor.

67charger440 · Dec 21, 2021

diesel_lv said:
It would appear both ports are manifold vacuum. That can be useful w an aggressive cam. If your engine idles smoothly with it disconnected, then you need to find a port that gives "ported" vacuum (no vacuum) when at idle to the distributor.

Thx for the reply, where could I find such a port?

dadsbee · Dec 21, 2021

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

67charger440 · Dec 21, 2021

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

No sir I am not. Edelbrock website stated the “blue” port is manifold vacuum but I get over 30” at idle. Was going to ask if something is wrong with the carb

Zeppelin264 · Dec 21, 2021

Sometimes you can get a vacuum source from the intake manifold itself instead of the Carb. Something else to look in to.

diesel_lv · Dec 21, 2021

67charger440 said:
No sir I am not. Edelbrock website stated the “blue” port is manifold vacuum but I get over 30” at idle. Was going to ask if something is wrong with the carb

If the pink is supposed to be ported vacuum, then you have your idle adjusted using the throttle blades and they are open enough to be giving manifold vacuum at that port. Need to reset the idle using idle bleed screws. I've never used that style of carburetor so hopefully someone who has can advise on that. Disregard Zeppelin264's comment. No offense to him, but it has no relevance in your situation.

pnora · Dec 21, 2021

30 inches of vacuum? That much vacuum it should be able to go to sleep without snoring.

AR67GTX · Dec 21, 2021

Never heard of a V8 pulling even close to 30” vacuum much less a 440. Have you tried a second gage?

Don Frelier · Dec 21, 2021

It could just be a rotor phasing or pickup gap problem as the distributor plate rotates.
I'd try another distributor

Jerry Hall · Dec 21, 2021

Could something be wrong with the advance plate in the distributor? I would start by checking the mechanical advance in the distributor ( vacuum disconnected). See what your advance is at idle and 2500-2800 rpms. As stated above your throttle plates could also be open also.

moparedtn · Dec 21, 2021

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

Dad is correct. The ported (or "timed" as Edelbrock likes to call it) is on the left and up off the throttle plate
some; the middle big port is for a PCV and the smaller, lower one on the right is for full time vacuum:

The orange circle indicates the ported ("timed") vacuum outlet; it will have ZERO vacuum at idle if the
carb is adjusted correctly. The other two ports have all the vacuum the engine generates, all the time.

Mike67 · Dec 21, 2021

I was reading an article the other day about these carbs and it stated that the timed port is only for emisions controlled vehicles. Sounds like changing ports should be you next step....

MIKESPOLARA · Dec 21, 2021

What is your idle rpm?

67charger440 · Dec 21, 2021

Mike67 said:
I was reading an article the other day about these carbs and it stated that the timed port is only for emisions controlled vehicles. Sounds like changing ports should be you next step....

Both ports have above 25” at idle

67charger440 · Dec 21, 2021

MIKESPOLARA said:
What is your idle rpm?

1000

67charger440 · Dec 21, 2021

moparedtn said:
Dad is correct. The ported (or "timed" as Edelbrock likes to call it) is on the left and up off the throttle plate
some; the middle big port is for a PCV and the smaller, lower one on the right is for full time vacuum:
View attachment 1211210

The orange circle indicates the ported ("timed") vacuum outlet; it will have ZERO vacuum at idle if the
carb is adjusted correctly. The other two ports have all the vacuum the engine generates, all the time.

hmm. Yeah that port is definitely not at zero at idle.

diesel_lv · Dec 21, 2021

If it's a mild 440, you should easily idle at 800-850. I'm running .541 lift 236 duration on 496 stroker. I idle at 850 in drive at 12" vacuum and 15" at idle in park.

Bee1971 · Dec 21, 2021

Can you get the idle down to 700 - 800 RPMs ? Or will the engine die when you turn down the idle screw

Also , do you have the rear back port plugged on the carb correct

67charger440 · Dec 22, 2021

Bee1971 said:
Can you get the idle down to 700 - 800 RPMs ? Or will the engine die when you turn down the idle screw

Also , do you have the rear back port plugged on the carb correct

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

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

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