Copper head gaskets can work, what most people don't do is anneal them prior to installation, this is what Mark was referring to with the Butane torch, If you just install them without annealing them I can almost guarantee they will leak. If given the choice I would use a stock or Cometic headgasket over the copper, but, in some cases that's the only alternative for special applications. One of my motors uses a copper head gasket, I use a hopcolite sealer and have annealed the gasket, it doesn't leak, of course I'm afraid to take it apart because I know it will next time.