What can happen if i tighten my valve covers on to tight?
In addition to what the others said, let me add this. If you do the job over again, take your valve covers and turn them upside down. Put the flange against a smooth, flat, solid surface (I use 1/4 plate steel I have covering the top of my tool box) and using a small hammer with a slightly rounded face, lightly hammer the flange back flat around the hole where they distorted. This only applies to steel valve covers of course, not Aluminum.