I'm rebuilding an Ford FE 390 Big Block that has been sitting in the back of my shop for about 20 years. Some pistons are rusted tight to their cylinders. I've been soaking the cylinders in brake fluid and liquid wrench for a couple months off and on and even taking a piece of wood and hitting the pistons head on with a hammer to break them loose to no avail. I've heard of using coca-cola but I just don't think so. Any ideas or thoughts?

 

If it's been sitting for 20 years and liquid wrench won't get them loose you're fighting a lost cause bud. Once you do get them out you're going to have to bore out the cylinders so wide to remove all of the rust it's going to be little more than a paperweight or boat anchor.

 

ya that sounds like a junker

try some pb blaster.....it works wonders on rust

 

forget all that crap. make a magic mix. one part marvel mystery oil, one part ATF, and let it soak for a while. if that dont make it pop, its dead.

 

air hammer?

 

Before trying heat and acid; break the pistons. The rods are the pricy valuable parts. You might be able to drive the broken pistons out [ break to either side of the wrist pins]. This one was so simple I didn't think of it right off. sorry.







You can apply heat to the pistons [ cutting torch ] [ DON'T DO THIS ONE IF YOU HAVE A CYLINDER FULL OF BRAKE FLUID] The aluminum will give up long before the block. Start in the center and work your way to the edge. Best done outside. Method #2 concentrated sulfuric acid, really, REALLY, want to do this one outside! Method #3 Hot tank it with caustic for about a week. If the caustic is fresh, might not be any pistons to worry about. Finally, the block might not be shot. I've done a bit with FE's. I've never seen an fe that couldn't be bored to stock 406 bore which is .080 over stock for a 390. Oversize 406 pistons can be had also. 406 pistons will also have larger valve reliefs for gt/pi/cobra jet heads. Hope this helps, do methods one and two outside, and use normal caution, take safety precautions. I lied, I did see one! The spirolock came out and the pin scored the cylinder to a depth just shy of 1/4 inch on a 300 v8 industrial engine. bob

 

x2, and i wouldnt say the engine is junk because the pistions are sized. ur best bet is to have the block checked for cracks and the crank mains line honed and have the cylinders bored just enough to remove the rust.

 

It's definitely not junk and the only reason it's not running today is because the crankshaft got burnt. Came out of a 65 GTA Fairlane. I have all the parts to rebuild it (except new pistons, new rods and a bigger cam) so all I really need is to get that burnt crankshaft out, bore out the cylinders, and give everything an acid bath.
What about glass beading/sand blasting the cylinders out? I have a glass bead gun and everything.

 

I wouldn't blast any gasket surfaces unless you are going to have it decked anyway. Good pistons can be had for a reasonable price but I can buy a running 390 for what a set of remanufactured rods cost. Good luck! bob

 

Have you tryed turning the crank bolt ? After you soak it. Give the crank bolt a try. Might be slightly better then beating on the pistons.

 

What I do is beat on it a while, then try and turn the crank with a breaker bar back and forth etc.... No luck yet, though I haven't done that in about a month because its been soaking in a mixture of brake fluid and ATF for a month. I think I'll give it another try tonight when I get off work. The crankshaft will move around alot and its just these two pistons holding it down because their rod bolts are impossible to get to because of where they are in their rotation.