Dual quad 440 jetting starting point

[gtxrt]

I've always been curious how the factory did the progressive. I tried different things but couldn't get rid of the lean front cylinders. While idling, using a IR gun, they were way hot like 650, 700 degrees and the back four were 600 or less. Maybe it's the manifold but it's an original factory one used on the 413.

were you using the mixture screws on both carbs. the stock iron intakes are bad look how short they are.

 

[khryslerkid]

were you using the mixture screws on both carbs. the stock iron intakes are bad look how short they are.

Yes, using a vacuum guage to get the highest vacuum on each carb. Start off with both set the same (IIRC 1-1/2 turns out) then go from there.

Plenty of hood clearance.

 

[gtxrt]

nice looking engine I bet the rest of the car is nice too.

 

[hoover]

I really appreciate all of the info.
The setup I am working on is a factory iron intake, and the carbs are some that i rebuilt. I did not realize there were differences in the idle circuit between 1405 and 1406.
I took apart 4 carburetors and made the pair with the nicest parts, not so sure i didn't mix the iidle jets up.
I have a 1407 and am thinking of finding another. Or the thought of a pair of factory afbs from 67 440 is another option.
Also, I do have the factory carters that came with the manifold. Those had no idle speed screw and i couldn't make them run right.

Given these options, should i be chasing the 1405/1406?

 

[lewtot184]

I really appreciate all of the info.
The setup I am working on is a factory iron intake, and the carbs are some that i rebuilt. I did not realize there were differences in the idle circuit between 1405 and 1406.
I took apart 4 carburetors and made the pair with the nicest parts, not so sure i didn't mix the iidle jets up.
I have a 1407 and am thinking of finding another. Or the thought of a pair of factory afbs from 67 440 is another option.
Also, I do have the factory carters that came with the manifold. Those had no idle speed screw and i couldn't make them run right.

Given these options, should i be chasing the 1405/1406?
View attachment 1677466

I think with you using the factory iron intake any jetting tips here need to be tossed. A ch28 and factory iron are not apples to apples. I'd recommend fixing the factory carbs even if you have jump through a couple of hoops.