I have a carb question for the Gurus on 2X4 Holley setups. Idle stalls.

[Keith Stevens]

I had Drew do my 2X4 Holleys from Carl's. ( Repo BJ-BK)  I went for a drive and out of the blue I had an issue with idle but runs fine about about 1600 rpm and up but wont idle at 900 as usual.
Because I have a Pertronix II I thought I may have a coil or module issue.  I did the rudimentary testing and found no faults, including verifying sold ground at the distributor. Factory C5AF 427 Centrifugal advance unit.
The voltage is at 11.5 ( not loaded) and the coil is at .05 Ohm.
However, I pulled the carburetors off and noticed that the primary carburetor ( Front) has a rubber vacuum cap on the nipple on the metering block and it was compromised.   Would that cause idle issues in itself?  I am unfamiliar with that port and the OE BJ-BK units do not have them.
Any guidance would be helpful!

[My427stang]

A metering block vacuum port is generally ported vacuum, and wouldn't affect idle speed, although you don't want it leaking

That being said, if the primaries are too far open, it would come alive and likely raise idle.

I'd email Drew, but what I would likely do for info for him is see if that port is alive at idle, if it is, look to see if there is anything binding, like a base plate gasket, etc, or another vacuum port leaking, PCV, etc

If not, close the primaries a little on each carb, see if it drops back

If it doesn't put them back to where they were, close the secondaries a 1/4 turn from the bottom and see what it does

[Drew Pojedinec]

If active yes, a vacuum leak can cause this issue.

Those repros are pretty lean at idle to being with, wouldn't take much extra unmetered air to cause an issue.
and yes Ross, the vac advance "shouldn"t be active at idle, but on those particular carbs, the vac port is often erm, randomly located

If I recall Kieth is in Texas which has pretty odd gasoline blends, it is May when they transition from winter to summer fuels, so could be more to it.  Same with ignition.

but vacuum leaks can always cause trouble.  I would go and vac check any other associated parts as well.

[Falcon67]

Also check your base gasket fit/seal between the carb and intake and/or any spacers involved.  Chased down many an odd idle issue there.  Same as above on the metering block port - should be "off idle" vacuum.  If you are pulling manifold vacuum for that, and the metering block port is threaded, I'd put a 1/8" brass plug in the port(s). 

[Thumperbird]

On the fuel delivery side of things:
Pull idle mixture screws out and give the inlets a light blow to clear any gunk and junk.
Worked for me 35 years ago on a Holley, why not now?
Same goes for bleeds as needed.

[Stangman]

Dont know how much gunk can be in them if Drew just went through them. I would definetly check the basics.
Base gaskets leaks,,, fuel dripping maybe dirt in needle and seat,,,timing,,, check where your idle mixture screws are,,,

[Keith Stevens]

It has been about three years to my recollection.  I had a fan clutch come apart and the blades wound up working like a fragmentation grenade and cracked the hood and the paint. A body shop had the car for two months.  I can tell the idiots made a mess of the meticulous restoration and rinsed the engine compartment off with a hose.  I wouldn't doubt that sanding dust wound up where it didn't belong.
Strangely enough This is the second time I drove the car since it was picked up. I did find some garbage in the screen and also in the well the power valve sits in. I pulled the bowls and blew some Berryman's through the passages, needle and seat, idle screws. I am going to pick up a new set of bowl gaskets and reassemble it tomorrow. I did notice that I had to open the idle adjustment screw up quite a bit to get it to idle at about 1500. It was unstable and would die out like it was starving below. If anything else comes to mind please post before I go to Summit in the morning.
I did check the fuel pump and turning the engine over it shows just over 6 PSI.

[e philpott]

When I went 2x4 with a pair 1850's the base plate didn't match the med 2x4's mounting pad good at all causing vacuum leak after a day or so because the PCV passage was way different the the mounting pad of the intake as theres no extra material on the intake to fully support the PCV passage , in my case I installed one of those Edelbrock 1/8th thick steel plates between the intake and carb . It covers the base plate way better than the intake did , might be something to double check but I'm not sure how different the base plates are between the 1850's verses Carls

[Drew Pojedinec]

I built these 6/10/2019.

It sounds like they just need a clean out based on your last post. 
a few metering block and bowl gaskets, a can of spray cleaner, and they should be good.

[Drew Pojedinec]

When I went 2x4 with a pair 1850's the base plate didn't match the med 2x4's mounting pad good at all causing vacuum leak after a day or so because the PCV passage was way different the the mounting pad of the intake as theres no extra material on the intake to fully support the PCV passage , in my case I installed one of those Edelbrock 1/8th thick steel plates between the intake and carb . It covers the base plate way better than the intake did , might be something to double check but I'm not sure how different the base plates are between the 1850's verses Carls

The later 1850s with the side 3/8 vac nipple are notorious for this.  There is just a tiny sliver for a gasket to seal on that corner.  I prefer to run a small solid spacer with those later baseplates.
His carb won't have that issue, but vac leaks can be troublesome just the same.

[Riderjeff]

I installed one of those Edelbrock 1/8th thick steel plates between the intake and carb.

Can you provide a part number or a link to where this can be purchased?