I have seen this done, very effective rust removal, especially in places a wire brush or sand blaster cant reach, like the chamber the cam resides in. Pure tungsten TIG rods work best, wont corrode or decay at all. And it's a very good thing you did this outside. This process produces large amounts of hydrogen gas, one spark and your whole house would have went kablooey. There's a method of separating the (-) and (+) so that you can capture the hydrogen produced. One contact produces oxygen, and the other hydrogen. A plastic drum would have made it easier to separate the charge. Most of the times I've seen it done people just use a big piece of rebar or other chunk of heavy steel that will stick up out of the water, so their wire isnt submerged.