I just bought a Zenith 228 carb from a salvage yard where it was exposed to the elements for many years. I've already ordered a rebuild kit for it and thought I'd get a start on disassembly and cleaning. The problem I have is with a rust and varnish encrusted pump piston firmly wedged in the casting well. I've already mostly destroyed the metal top to the piston trying to remove it. So far, the casting remains undamaged. Right now, it's soaking in some clean gasoline awaiting further progress. I think that I might be able to run a 1/2" tap into the inside of the pump piston to thread a bolt into it to give myself something to grab onto. Or maybe epoxy a bolt inside the piston. So, do I soak this carb in something stronger than gasoline? Apply heat? Attempt to grind, file, or drill from inside the metal remnant of the pump piston? Something else? It seems that the clearance between piston and casting couldn't have been more than a few thousandths of an inch under the best of circumstances so there's not much margin of error.
I'd really like to salvage this project. Any thoughts would be appreciated!

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