I'd like to know what you guys do to the surface of an aluminum block/heads...polish, sand blast, paint? I know what I'd LIKE to do on mine, but not how. What I'd LIKE to do is have it natural, but I know natural is subject to stains, corrosion, discoloring, etc. If I could get it all cleaned up, and one consistant finish, I could seal it with some sort of clear, so it wouldn't stain corrode, etc. Question is, HOW to get it to a nice, as cast finish, and then WHAT to seal it with. Would walnut blasting do the trick...and give it that nice, smooth, sheen? Sandblasting leaves a rough, porous finish...not looking for that type surface...
Can't say with any first hand experience but Flatoz told me soda blasting is the go on aluminium. He said it cleans up pretty easy and doesn't stain. Pete
Actually Pete it is not soda blasting but is a very fine glass bead blasting done wet with a detergent or chemical of some sort in the water. It seals the pores in the aluminium so that the oil, grease etc does not soak in. Flatoz used it on all the alloy on his blown flathead and it gives a satin finish- if you're not a gold chainer looking for bling it's ideal. The guy that does it got the machine to do British bike bits and you just know how oily and greasy they are LOL. The machine is made in England but now I think they are made here in Oz. I had a twin carb slant manifold which was such a bad casting that it couldn't be polished and I got it done and now it looks like it is Jet Hot coated. Very happy with the result. swifty
If the aluminum isn't in really bad shape, I'll clean off all the grease/oil with Simple Green (I usually don't dilute it), and scrub them vigorously with a soft bristled brush. This will take off about 95% of the staining. After that, I use the plastic style wire wheels on a die grinder or drill. They have sort of an artificial shine when done, but give it a day or two and they will look more natural. After that, I will spray them lightly with automotive clear, just enough to seal the pores. I have yet to have any of it burn off or flake, though this probably won't work on engines that have the exhaust port visible on top of the casting (Pontiacs, some big Fords, etc).
Castings often done anodize well, and many of the alloys used for castings don't either, so even if you were willing to pay for that it's probably not a good option. Any coating will eventually fail. The smoother the finish on the part, the sooner that will happen. Some coatings are more durable than others, but the more durable they are, the harder to remove and re-do when the time comes. If the surface isn't too smooth/shiny, clear powder coating is probably the most durable(and also hardest to remove) thing to use. I suggest you achieve the finish you want and just keep it clean, or at most a thin spray of uncatylized clear acrylic enamel(removes with lacquer thinner). If you do decide on powder coating, make sure all holes and machined surfaces are well masked or plugged, and remove any powder coat the does get onto machined surfaces.
I like to glass bead my aluminum and then lightly coat it with Krylon dull aluminum spray bomb. I have done it to 200S Americans for years and it holds up good and takes away the stained and uneven look that most cleaned up cast aluminum has.
While clear powder coat is somewhat durable it will yellow which drives me crazy. we have been using a clear ceramic coat which holds up MUCH better than the powdercoat ....and it will not discolor. The ceramic coat creates a chemical bond with the aluminum and will not crack, fade, peel. The guy who does it for us has had stuff on the street for 6-7 years and it absolutely looks as good as the day he put it on. Now if you ever want to take it off.....good luck.
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