the real issue with 6paks is the screwed up idle circuits. if all your doing is racing maybe you can just do the basics, but for good street driving you really have to go after the emissions built into the circuits.
Could you elaborate on this statement. Since this is my thread, I guess it’s ok to highjack it. I have to agree six pack are harder to tune than most. The factory plugged up the idle adjustments screws for the outboards and the center metering block can give lots of trouble with the idle well tubes. The new bilet metering blocks really help the idle circuit, but they don’t look Stock. I’m all ears.
chrysler built their emissions into the carbs and ignition. the 6bbl carbs have a somewhat unique idle circuit. the secondary carbs have a mixture screw and probably so for a lean idle burn. the center carb, which i think is the real culprit, has the idle jet tube in the main well contrary to conventional holley performance carbs. that idle jet is .023" and the idle air bleed is about .062". the relationship between the two is heavily biased towards a lean burn. the idle jet should be at least .031" for that .062" air bleed. in my opinion there's no way the center carb, which is the brain of the three, can supply enough low speed fuel. so this means we have to over compensate the end carb idle fuel to make up for it. normally this can be made to work, done it many times, but i don't think it's right and i've never got a good clean burn doing it. if i ever do this again i'm going to open up the center carb idle jet and maybe use a screw in air bleed for the center carb. another option is simply change the center carb metering block. promax has a metering block but i'm pretty sure you can't use a vacuum advance distributor with it and i use a vacuum advance. another option is an aftermarket universal metering block with the idle jet in the conventional location. back in the day some folks would put piece of lead shot in the center carb idle air bleed and drill that out to .046". this would put the air bleed and jet in a better relationship but i think there still may be a volume problem i bought a universal metering block from quick fuel (IIRC) that will do what i need and if IIRC correctly has a .032" idle jet that can be easily opened. you'll still have to get into the secondary carb mixture screws for adjustment whether you stick with what you have or change parts. looking ahead will only make the start up and final tune easier. you may have some main metering issues with the 440 metering plates in the end carbs but that shouldn't prevent a good tune for driving.
