Need to free up a oxidized carb

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Wylie, Texas
I haven't done a lot of searching on this, I'm working part time for a friend of mine who owns an auto shop.
We have an old 4bbl carb off a vintage vehicle that has been exposed to rain & moisture long enough to seize everything on shafts or linkage solid. We need to free & clean it up. What kind of a penetrant or solvent would be recommended? It's torn apart, mainly it's the butterfly shafts frozen in place and general aluminum oxidation.
Thanks
Steve
 
I think you are going to have to remove the frozen shafts and clean them up. To get them out, you'll need to patiently soak the throttle body and choke/air horn in penetrating solvent. The throttle and choke plates on pre-Loctite era carbs are held in place by solid brass screws that are peened over. You will need to carefully file off the peening to remove those screws. You'll need to locate a screw specialist for replacements. With the plates out, you can hopefully pull out the shafts. If the plates are damaged, you'll need replacements. If the shafts are not badly eroded, you can clean them with a buffing wheel. If they are eroded undersize, they can be plated to increase the lost diameter. If removing the shafts damages the holes through which they pass, there are carb specialists who insert bushings to replace the worn holes. I have used glass beads and also walnut shells to clean carb bodies. But the use of glass beads requires the very careful sealing up of all internal passages and thorough cleaning with high pressure water. If you have an unplated carb like a Carter AFB, you'll be fine with the finish after bead or walnut shell blasting. If it is a Holley, you'll need to replate with zinc dichromate. You can actually buy the electrodes and solution to do the plating yourself. It's possible to have a very positive outcome restoring an old carb but it is a great deal of work. You might do well to first determine if the carb is rare enough to justify the restoration. If you go ahead, keep us posted.
 
What kind of carb is it? If the throttle shafts and what not are really bad you might be better off finding a core on Craigslist or ebay if #'s matching is not a problem. You can get new throttle shaft bodies for Holleys still.
 
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