In cleaning up used aluminum intake manifolds, there are a few considerations that don't apply to cast iron or steel parts because aluminum is softer than ferrous metals. You can't blast them with sand or other more abrasive media because it will change the surface texture and can obliterate casting marks and part numbers. Sand blasting also leaves the surface more porous than before, making it more likely to retain dirt. When I first started to research ways to clean used aluminum manifolds, I found a lot of YouTube videos that described cleaning them with solvents and wire brushes. Most of these seemed to be less than completely effective, and still changed the surface. Eventually I came upon vapour blasting, which is blasting with compressed air, water or steam, and usually small glass beads. This was said to have the advantage of removing dirt and stains without damaging the substrate or removing casting marks. It also seals the surface and leaves it smooth - cast surfaces retain the original texture, and machined surfaces come out almost shiny.
I had an original 1972 455 HO intake manifold, and a 1971 service replacement unit, both of which had been used. The SE unit was in very good shape, and its aluminum surface was so consistent, at first I thought it had been painted. I also had an original Herb Adams VSE cast aluminum oil pan that I will be using that I wanted to clean up.
I found a local custom motor cycle shop that had a vapour blasting set-up. They charged $20.00 Canadian per 10-minutes of time spent in the vapour blaster. It ended up being 9 units, so 90 minutes, plus a $20.00 shop materials fee for the glass beads, and tax - $210.00 CDN all in. Below are a series of before and after pictures. I was really pleased with how everything turned out. The manifolds look practically brand new, almost like they have been painted, but they swear they have not. The machined surfaces where it mounts to the heads and carb came out beautifully smooth. The oil pan as a little rougher casting, but it still came out very nice.
It's important, of course, to clean everything up after with soap and water and compressed air - tiny glass beads would not be a good thing to introduce to an engine either through the oil or through the intake system!
1972
1971
VSE
