Triumph Repair: 80 Spitfire intake manifold, dremel tool, triumph spitfire

Question
I have a 1980 Triumph Spitfire which I have restored to it's original glory.
In the process of doing so I wanted to clean the intake manifold, because it was terribly dirty. I found no cleaner that would take the dirt off so I used my dremel with a wire brush to do the job.
Now after finishing I was told that I have made a huge mistake. Someone told me that the manifold is not solid aluminum, but a aluminum alloy which was coated at the factory so it would not rust. Is that true, and if so in the process of brushing it down to shining aluminum, will it rust, and look like crap again in the future. If that is the case I may as well paint it before the rust appears.
What would you suggest?

Answer
Hi Ed,
It is a simple test to see if it is aluminum or not. One by it's weight if it were iron it would be heavy. And the sure test is to stick a magnet to it. If it don't stick, it is aluminum. I don't remember ever seeing a iron intake manifold on any Spitfire, not that I claim to have seen every Spitfire made. It sounds to me like someone is trying to pull your leg.

I have seen aluminized coatings put on iron but only to prevent rusting but you could not take it off with a Dremel tool and wire brush. It was electro-plated like chrome is put on. It would take a grinder / sander to get it off. Just do the magnet test and don't worry about it. If you can take any coating off with a Dremel tool with a wire brush then it was not plated but just painted so all you need to do is get a spray can of aluminum heat paint from any hardware store and repaint it after you finish cleaning it.

All metals corrode to some extent but iron is the only one that rusts and I never heard of any aluminum alloy that had any iron in it. They do coat some aluminum with a sealer because aluminum can be porous. But even then the sealer usually seeps into the small holes and would not be affected by cleaning and polishing the out side. I bead blasted my manifolds I made then put sealer on them mainly for looks.
Howard