A guy here in hays uses that method to clean up engines. He'll put coroded engines in the crockpot in Byron airplane fuel to clean them up overnight then he'll shoot carb cleaner in them. They'll fire right up after a little work on them and they run powerful. No damage is caused by it whatsoever. The dirtier the fuel gets the better it works. Personally, I just save my fuel in a plastic ice cream container with the plastic lid and handle and I just soak them in there and use steel wool and toothbrush to clean them up. The crockpot idea is a lot easier to do, but he also uses an air compressor to blow all the gunk out.
Clint

PRACTICALLY BRAND NEW LOOKING ENGINES