With a high overlap cam, ignition timing helps clean up the idle. 20 degrees as a ballpark. With timing set, carb tuning helps. Still, there may be some smell. I have it with a 243 degree @.050 cam. Nature of the beast. Probably not an issue with intake duration of ~220 degrees or less.
I hear ya. Mine is a custom Bullet cam with 255@ .050. I have a custom carb that will do anything i want it to as far a getting rid of a rich condition. It reeks ( more or less)no matter where i put it. My last car was a 5.0 mustang with fuel injection. With the cats you could stand behind the car all day. With the cats off via off road h pipe it would still gag ya, and it was clean burning.
