gibbo69olds

So I have been messin around with the timing on my 69 cutlass with a 455 in it and have noticed some interesting things that I didn't think I would see. I have checked tdc and the harmonic balancer does not appear to have slipped. I have tuned the engine for 10 degrees and it seems to barely want to stay running. What concerns me more is that when I rev the motor or even stand behind the car I see like a white or gray smoke out of the exhaust. Any ideas?