At times it seems the engine in my Challenger is running rich, the exhaust smells of gas. The exhaust tips are also black with a soot/residue build up. The engine is a fresh build (approx 700 miles on it), takes no oil, and when warmed up runs and idles fine. When driving and I open her up the performance is good. If this is a "rich" running condition what is the best way to lean the engine out.
Thanks

How fresh is the gasoline your driving it on? Todays pump gas won't and doesn't last very long when sitting I've seen pump gas go flat in the cars gas tank in less than 6 weeks up here in the winter It won't last that long in the heat of summer, below 90 F during the late afternoon, down to around 60F or colder at night IHTHs

Read the 6 pack tuning guide in the tech section.

If you are tuning using the factory timing at idle, you're miles off from a good tune up.

Definitely check out the "guide" cuz 3 carbs complicates things. in the meantime I would check some basic stuff: float saturation float levels needle/seat dia FUEL PSI idle mix screws. When is it running rich? cold hot what RPM part or WOT

What duration camshaft?
what power valve?
Has it backfired and blown the power valve?
what fuel pressure?
What idle speed?
Are end carbs fully closed at idle?

what both Robert and nanket said. you need to know your fuel pressure and your vacuum/power valve. how open do you have the mixture screws on the outboards? do you have the throttle plates FULLY closed at idle on the outboards? what thermostat are you running.

in other words - read and follow the tuning guide and adjust from there. it gives you an awesome baseline

On my 440-6, I removed the power valve and installed a Holley screw-in block off. I had to richen up the jets 3 sizes larger (trial and error) and the engine ran great after I did that! I initially tried several different spec power valves, but they all dumped too much fuel at the wrong time. I was running long tube headers, and a Sig Erson 484/292 hydraulic cam. It doesn't cost much to eliminate the power valve, and the guy at the speed shop laughed at me... saying it was a huge waste of time. (a Chevy guy) Boy, he sure did apologize after I blew the doors off his friend's Camaro! Those were the days when Mopars got no respect (1980's)

Right now I am building a 360-6, and I am going to try that same set-up again.

THIS IS VERY BAD ADVICE

Six paks require a procedure or they don't work. That's it.
Procedure: noun: procedure; plural noun: procedures
an established or official way of doing something.

THIS IS VERY GOOD ADVICE-this works.

read this or stay on the porch

Hi Tom_Quad,

If you came back to read my reply, I'm not trying to pick a fight with you, as I see happens a lot here on Moparts. Everyone is entitled to their opinion. I just want to say that I did not advise anyone to do the modification that I performed on my particular six pack. I simply stated what "procedure" worked great for me. People modify cars all the time... the term "hot rodding" comes to mind. Heck, Holley offers an assortment of parts to modify their carburetors. If the so-called six pack procedure worked great on every six pack engine in existence, that would be awesome! I don't know if the same modification will work on my 360 six pack, but it won't hurt to try!

Have a great day!

Another thing to do after you drain out the old gas and put in new fuel is to start and warm the car up so it will idle in nuetral okay, if it still stinks like raw fuel turn the idle mixture screws in the center carb. SLOWLY until the idle RPM satrts to drop, turn it back out 1/8 turn on that side and then do the other side If that doesn't cure it then you will neeed to take the back carb. off the intake and adjust the idle mixture screw in the base plate so it GENTLY closes all the way and then back it out 1/4 to 3/8 turn out from fully close, do the same thing on the front carb and see if that helps
Six paks rock, especailly when set up properly
Another thing to check on all three carbs is that the throttle plates are close so the transfer slot in the carbs. are not expose at the idle speed the car idle at, you need to pull the carbs. off and look at the throttle plates to see how far they are open, if any of them are opened far enough to expose the short, narrow transition circuit slot in the middle of the front of the carb. main body just above the throttle plates when they are closed all the way it will cause it to idle on both the idle circuit and the transition circuit Which makes it run richer than normal when it is on the idle circuit only Lots of misinforamtion out there, especially on Mopar sixpaks, and lots of gremlin may have worked on your sixpak before you got it Let us know your results please