Car is a 67 Chrysler 300 with 440 hi performance engine and in-line dual quads (primary is an Edelbrock and secondary carb is an original Carter AFB). Just recently had FBO's ignition system installed (dizzy, ECU, ballast, coil..using Mopar plug wires for electronic ignition and J12YC Champion plugs). The ignition items (timing, ect) are set up as FBO suggests.

Car runs pretty nice for the most part, but after the ignition upgrade I decided to try my hand at some carb adjustment. The car was running primarily on the front carb (Edelbrock) for idling and the secondary carb pretty much went along for the ride except for WOT excursions. The rear carb is a Carter and has mixture screws and a big screw between them that is an "air bleed" of some sort, it controls the air admitted at idle and not the fuel.

I used a vacuum gauge and starting with the rear carb, set the mixture and "air" screws till I got maximum vacuum and rpm. After that, twiddling with the mixture screws on the front carb didn't accomplish much so they are pretty much left were they were.

Car is idling nice and running good now. Does seem to be idling a bit too fast. The back carb does not have an idle speed screw, only the front. I backed off the idle speed screw on the front carb and it had no effect. I finally backed it all the way off the cam... Any ideas were to go from here???

Here's the interesting part. I was using a nipple on the check valve for the brake booster to get my vacuum signal. Whenever I pulled the hose off and the car was sucking air from that hole, the idle speed up but got a bit shakey. Does this mean the car is still running to rich??? What does that mean......

By pulling th vacuum hose off it will make the car idle rougher.

Maybe back the timing down a bit, you shouldn't have to do that though unless its set too far advanced at idle. Maybe it performed better there before though because of the improperly adjusted carbs?