The info in post #18 tells me that Chrys was not happy with the idle system....because they kept changing it. You only do that if you are trying to make it better.
I think that is a bad conclusion. Back to lew and others comments. Words matter. Your orig post stated "didn't have adjusters for idle".
Idle setting screw and idle mixture screws are two different screws. You are correct the "IDLE MIXTURE" screw are hidden on 68 and up.
Not sure why Geoff thinks they were not happy with idle system. If your going to talk carbs you need to accept that Post emissions carbs HAVE to be different than pre emission carbs. First by CA Law starting in 1966 then Federal Law in 1968.
No emissions standard on 66 Hemi even in CA. They were given an exception. 67 CA Hemi had CAP carbs to me CA standards. 68 all carbs were emissions carbs.
66-67 carbs are bypass carbs. An air screw to by pass throttle valve for idle setting. Plus idle mixture screws to adjust idle mixture quality. Starting in 68 that won't fly anymore because it would allow emission standards to be over ridden.
So in 68 the Front carb which normally
does not contribute equally for idle in a hemi has idle mixture set at Carter on a bench and then plugged so that owner can't adjust. The rear carb has idle mixture screws accessible, but with a locking device that allows a limited range of mixture adjustment to remain in federal specifications. Rear carb idle mixture goes lean along with distributor changes to keep Idle emissions in spec and control cruise, and deacceleration emissions.
Minor jetting and rod changes did occur driven by testing and trying to improve distribution of fuel with the street manifold.
68 and up rear hemi carbs actually have secondary idle circuits as well. Fixed bleed holes in the throttle bore to allow fuel to flow before and after secondary valves open followed by normal discharge port AFB have to help transition to secondary main when air valve opens.
So it is NOT some dissatisfaction with idle circuit that forced a change. If fact the 66-67 carbs were the carb to use for drag racing with a street manifold. Including Vanke mod. Of course, the cross ram with Holley's were a better set up for the High compression SS cars though.
For street hemi you idle off the rear, but best to add 50 to 150 RPM from the front, dialing the rear back to set your limit. This prevents any lean or misfire with front cylinders.
For bigger modified motors you can try your direct linkage and equal idle, but make sure you looking at how fuel is distributed and no cylinders too rich. Especially at acceleration since you run the risk of pooling liquid fuel running back to rear cylinders.
