I put new edelbrock valve covers on my 1970 cutlass supreme and in a short amount of time they have already started rusting in certain areas. Are their valve covers know to be such poor quality. I bought them over another brand because I thought they had good quality products and cause they are advertised as triple plated chrome. When I got them I was not happy with the quality of the chrome plating. I am going to use chrome polish on them to get rid of the rust. Has the quality of their products gone down recently or has it always been this bad?