If you need a quick fun project, then try the reverse electrolysis rust removal! Lots of fun.
Just do a search on the forum for this topic. I took some old hassler shocks from storage that had surface rust. The first pictures show the start of the process with gas bubbles beginning to surface. The last pictures show after 12 hours the dirty rust debris from the sacrificial metal spike. This really works well. Great to show the grand kids basic chemistry too!
I used a 45 gal trash can to remove the rust from my running boards. Also works good for long parts.
For smaller parts I use a 5-gal bucket and a 3-gal container. What I like about electrolysis is that it preserve the character of the part. If I beadblast then it changes the appearance.
What can I use for an aluminum drum valve corroded into a brass carb body?
Your first picture looks like it has a spindle, or some other spindle like shaft. I would recommend not using electrolysis on any steering, rear axle shafts or internals, or engine internals because of the possibility of hydrogen embrittlement.
Hydrogen embrittlement can result in a delayed brittle fracture.
Ted thanks for the advice. No just hassler shocks the item to the far right is a big metal spike used as the sacrificial anode
If you are not in a real big hurry to remove rust, I have another solution. Take one gallon of "feed grade" molasses and mix with ten gallons of water. It won't take off grease or paint but will remove rust in about two weeks. One of the advantages is it goes places that you can't sandblast. Naturally you will have a real sweet molasses smell but not too bad. Once in a while you will need to stir the solution. It also will last a long time. May have to add water due to evaporation. Feed grade molasses can be bought at the Co-Op or at your local store that has deer hunting supplies. I have used this for a long time and have been very satisfied.
If you don't want to save the aluminium drum put the carb body in a solution of caustic soda and water.
Its used as a paint stripper among other things.
When I was an apprentice the painter soaked his spray gun in a caustic solution to clean it of accumulated paint. When he checked it the next day only the brass parts were in the solution the aluminium had dissolved.
Yeh, thanks Peter... The drum is the heart of this Master/Miller carb. Kroil hasn't touched it yet, nor has 250F.