6 Barrell A/F help

[clazar]

I'm having trouble adjusting the a/f ratio screws on the center carb. There is no difference when either side is adjusted. I can screw them all the way in & no change. So, what needs to be checked or fixed ?? I'm also getting 15 on the vacuum guage. And strong gas smell after shut down.

 

[turbine68rt]

What is your idle rpm?

 

[davek]

your vacuum does not move when you turn in or out the mixture screws?

 

[70sixpkrt]

Try adjusting the outboard carbs first.

 

[clazar]

What is your idle rpm?

Appx 850

 

[clazar]

your vacuum does not move when you turn in or out the mixture screws?

Doesn't move at all. But I set the screws appx 1 3/4 turns out.

 

[toolmanmike]

This video may help if things are mis adjusted.

 

[clazar]

Try adjusting the outboard carbs first.

I know there are no a/f screws to adjust on the outboards. And the linkage is adjusted ok. What else to adjust ??

 

[PurpleBeeper]

I know there are no a/f screws to adjust on the outboards. And the linkage is adjusted ok. What else to adjust ??

Side Note - There ARE a/f screws on the outboard carburetors. They are on the front of the outboard carburetor baseplates behind some lead plugs & they are often frozen in place. There's a good chance you'll need to uncover & adjust these a/f screws (idle mixture screws) at some point.

Your current problem - your center carburetor idle mixture screws don't do anything (99%) chance because the center carb throttle blades are too far open (exposes and idle slot)....so, the goal is to get that center carburetor more closed while still maintaining your idles speed (850+ rpm is good) Usually, you'd adjust the idle mixture (a/f screws) on the outboard carburetors to get the idle up, then close off the center carb a little bit, & re-adjust the carburetor linkage.....and repeat. At some point, the center carburetor will be closed off enough that it covers the idle transfer slot (name?) & voila! The center carburetor idle mixture screws will start working.

Side note... I did have a OEM center carb that I rebuilt and one side wouldn't adjust no matter what I did. I rebuild the carb again & blew air up the hole behind the non-functioning idle mixture screw and a big glob -of oily snot came out....only a 1% chance you've got anything like that - see above =

 

[lewtot184]

The idle jet is too small in relationship to the idle air bleed in the center carb. This is why the end carb mixture screws have to be opened up. I've preached about this on this site and moparts and it all falls on deaf ears. Fix the center carb idle circuit first.

 

[Geoff 2]

If you have 15" of vacuum, the mixture screws do nothing & smells rich, I suspect one of two things:
- carb is flooding
- the dreaded Holley met block gasket fiend has struck. Cracked, leaking or blocking passages.

 

[Mopar Miki]

there is no easy answer to these threads

 

[33 IMP]

the problem is likely the end carbs idle mixture screws. Purple Beeper covered it.
Front two carbs can be adjusted, rear carb has to come off, or you need to get the special tool made just to adjust the mixture on the rear carb while its in place.

sorry. Found the guy that did the adjustment tool and screws for the rear carb. He was on the A-body side, but hasn't been on there since 2016.