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To add a little to that, I had some cheap $20/pr Edelbrock chrome "Signature Series" valve covers on my truck that I bought to replace what looked to be equally-cheap "Powered By Chevy" chrome VC's. I bought new cork gaskets for them and never had a leak issue. I have since replaced those with Dart chrome VC's that most likely come out of the same factory as those Edelbrocks, the Powered by Chevy ones and any other cheap, chromed stamped steel valve covers and they too seal fine. I again used the cork gaskets that came with the Darts. It would seem that the leaking VC issue of SBC's is best solved with a thick gasket like the cork ones.But yes, you want 'centerbolt' valve covers as previously mentioned. Lots to choose from when you look for that term.