I’ve rebuilt a 396. Went all out: 40 over dome pistons - the works. It runs with a 650CFM Edlebrock. When starting cold and revving after warm up the exhaust leaves thick, black soot on everything within 3 ft of the tail pipes. Also have a high idle manifold leak whistle but the manifold is sealed like a duck’s butt under cold water. Any suggestions on how to get rid of the (Most of)black soot, and what is the whistleing?
Ported? With a high duration cam and headers? Cool. You’re moving a lot of fuel there.
Perhaps you could lean out the Edlebrock. Check the manual for the adjustments.
Another thought…high compression means having to push the spark through high density mix…that takes more oomph…do you have a high performance ignition system?
The whistling may be a characteristic of the manifold’s fluid dynamics. Have you checked for leaks with some gas spray…or ether.
OK4450 has rebuilt more motors than Carter has Little Liver Pills. OK4450?