No compreesion on #8? - You have a bent valve stuck open. Take off the valve cover and look at the cam lobes as they contact when you crank engine over by hand. I will bet one valve or both on #8 are not moving. Time to pull the head. DO NOT TRY TO START THE ENGINE UNTIL THIS IS RESOLVED. As it is an interference engine - the stuck valve can puncture the top of the piston.