Hey I have a 1974 Firebird Formula with 400 engine backed by a turbo 350. The thing is that birdie is living 5000 miles from its original home, in a country called Turkey, and helping people oh knowledgeable people is nearly nonexistant here around. Here is the problem which is preventing me to drive it daily. The car has a stock 400 with stock internals and 4X heads. Only modified items are Performer Intake and 1404 500 cfm carb. Symptoms: 1. Each time I crank the engine, even when it is hot, a black cloud is rising from the tailpipes. 2. While cruising, when I go pedal to the metal a burst of black smoke is rising from the pipes as if I were driving a diesel. 3. Man it is gobbling the gas. And the gas prices here are nearly 4 times of what I should pay in the States. 4. Guzzles the gas but no performance. 5. Also hard starting is another issue. Some local mechanics said that the jets of that carb are big and that are pouring more gas than the engine needs that I should change them with small ones. But they did not mention anything needles or other parts. I suspect that some gearhead have previously changed those jets in the quest of some performance gain but messed up the tune. Dear friends I would like to hear your opinions and experiences cos there are no one here to help.