we tried the citric acid solution on some parts after reading hambers success. it works very well. we put a very rusty crankshaft and some 8ba manifolds in 3 gallons of water to 1 cup of citric acid. 2 days everything was clean. the residue brushes off with a paint brush. thank you for posting this. we don't have to buy expensive solution at the hardware store when we can make the stuff for pennies. we won't be passing on rusty parts at the swap meet anymore. i mean, when we get to go to a swap meet.