Idle mixtures (CO levels anyway) are sensitive at idle. I managed to get mine down to 4% with a CO meter. Doesn't take much to go to 6 or 8%.

Sherwood

Not a 911 carb expert so only fwiw.
I'll assume floats are set and you don't have a clogged idle jet.
I'll also assume your dizzy initial & curve is carb ok.

Try the 60s at a mix setting of 2 1/2 turns on each cyl. ie: keep all settings =

Repeat at 3 turns. all being =

A quick run around the block is ng imo. I wait for a full 10mi street warm up. An idling engine never really warms up.

I think you gotta try 60s for more info

once I got the carbs ok I was able to tweak the accelration flow for more zoom without affecting the accelerator pump mechanical geometry. I can almost bog the engine it's so rich on acceleration. I gotta control the pedal 'cause it comes on almost like a mechanical secondary Holley.

Big Kudos to you guys! I spent ages getting the float levels perfect and this solved the problem! I now know what Tyson, Sherwood, Warren all mean when they talk about just how critical they are :) I'm sure I still have some finer tuning to do... but at least I can drive the car to get fuel. I went back to .55 idlers, but will pick up a set of .60 for further tuning.

Thanks again