there is a loud noise from valve cover or something wrong with the gasket on 1992 Honda Accord

I try change a valve cover for my honda 1992 accord after the change there is a like a machine gun noise that goes off after a minute i turn on the car. Please help me I have no idea what it can be

Asked by for the 1992 Honda Accord
Could be a big-time scary problem with the valve train or valve seats. Seek professional assistance--don't damage the engine!