weird smelling smoke!?! please help!

so I have a 318 with eddy heads thats running about 9.8:1 compression. I put a holley 670 avenger on months back and it made an amazing change in performance over my old edelbrock 600 cfm carb. so anyway's, whenever my buddies are cruising behind me they said when I floor it or just goose it a little it blows smoke that doesn't necessarily smell rich and for sure doesnt smell like oil but they said there is sometimes a very small tint of blue in with the smoke. they said the smell is indescribable almost as if im running a different kind of gas. any ideas? I checked my compression, all the cylinders are all the same, and im fairly certain its not the valve seals since the heads are brand new plus im not losing any oil. I also tried jetting down my carb but even going down one number on the primaries and secondaries made it start back firing a little out of the carb, so I went back to stock jets. My timing is 16 initial, and 42 total which seems a little high on the total side but I dont know how to make the total lower. one last thing, when I was running my cast heads my motor would ping a little so i was told to run cold plugs, but now that im running aluminum heads should i go back to a hotter plug? sorry for the novel. but any help would be greatly appreciated! thanks -Kory