Hot Rods Rust in cylinder head water jacket

I purchased a set of heads that were rebuilt awhile back. The PO said the heads only had a few miles on them but the engine was run without antifreeze just water. It is unknown how long the heads were on the engine but long enough to have rust and scale to build up in the water p***ages. The mating sufaces are in incredible shape along with the rockers and springs. I need some advice on how to remove the rust. Thanks

 

Wire brush should fix ya up.

 

I'll give this a bump because I have the same issue with a Model A Winfield head. Surface is fine, but I can see rust deep in the water p***ages. A wire brush isn't getting in there. I don't know whether to leave well enough alone and run it as-is, or drop the thing in mol***es for a couple weeks and then flush it out. Interested to hear what people think.

 

I'd use "Evaporust" or more likely, "Rust 911" concentrate (cost reasons). I used it to flush my '51 Merc engine and it came out great. Here's a shot of the interior of the block through the water pump opening after that flush.

 

I have used vinegar to remove rust from marine manifolds before, but I completely submerged them in a bucket. You could try taping off the gasket surfaces and setting the heads up so you can fill just the water jackets.

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Just did a 5.0 ford that was run with just water . Used evaporust and it cleaned right up.

 

Bottle brushes just like you use to clean oil p***ages when you are rebuilding.

 

I use Oxalic Acid which is also known as wood bleach (used for removing marks from boat decks etc.) It comes as a powder. I just mix it with water and soak the part until the rust is gone. It only dissolves the rust, doesn't attack the metal at all. Maybe not the best example, but here's a before and after on an old sump pan I did a while ago.

The rust turns to a kind of green sludge on the part, so I just agitate the part in the tank once in a while to keep the de-rusting going.