Check the oil and see if there is any water in it. I had a similar experience on my small block and wound up with a cracked head.
Definitely check the rubber exh. hose. The inside was burned on both hoses on mine and the exh. flappers were burned too.Tinkerer said:Exhaust riser gaskets, exhaust flappers, rubber connector hose between the manifolds and the tips.
( check the inside of the hose - it may look normal on the outside )
I would say kind of black, for sure not white or blueFyhr Factor said:I would deffinitly change the oil..
What color was the smoke.??? white, blue or black.??