I picked up a 350 in great shape with a top end tick. I have set the valves to .08 at tdc on the compression stroke and checked the timing chain all good. When watching the valves work at I turn it over the intake isn't opening till late in the stroke and closing just at tdc. The exhaust opens as soon as the piston strokes down and closes at the bottom of the stroke and then a whole stroke with no valve movement. The cam timing marks are lined up with the crank being at tdc and the lobes are down. What am I missing?