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That is the question. When my engine was pulled and sent off to the machinist the block was "boiled" and it came back looking pretty ugly. It is nice and clean mind you but ugly none the less looking blotchy and stained. Has anyone painted their block and if so, what color would bring it close to original? I don't want to devalue the car by painting the block but on the other had I want it looking good too. Open to any suggestions. TIA, David
 

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Check out the "High Tech Engine Enamel" from Seymour, #En-71 Dull Aluminum. You'll find it hard to distinguish from freshly bead-blasted cast aluminum.

I remember way-back-when, when I saw my first painted aluminum block: FAF Ferrari had just redone a V12 and I figured "If it's good enough for a Ferrari..."

Chuck

HI-TECH® ENGINE ENAMELS - Seymour of Sycamore
 

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The block is blotchy because it was boiled in caustic soda. Sometimes, not always, it can be cleaned of the blotcth with organic acids used for aluminum weld preparation. This liquid is painted on oxidized aluminum, and it bubbles a while then stops. Rinse with very hot water, and repeat a few times.
The block below was blotchy and cleaned as above.
 

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Discussion Starter #4
The block is blotchy because it was boiled in caustic soda. Sometimes, not always, it can be cleaned of the blotcth with organic acids used for aluminum weld preparation. This liquid is painted on oxidized aluminum, and it bubbles a while then stops. Rinse with very hot water, and repeat a few times.
The block below was blotchy and cleaned as above.
That looks pretty good however my mechanic let me know he had already started re-assembling the engine so water is out of the question for now. Could have acted sooner had I known.
 

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Hydroblasting!

I had all my aluminium parts including the engine hydroblasted. The finish is awesome and being a peened finish no need for any protection and cleaning is a breeze!
 

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I think unless it runs in a corrosive environment, the aluminum stays pretty clean as is. The block I cleaned in 2008 looks the same today.
 

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We used to use dilute muriatic acid. VERY dangerous stuff. It etches glass and will disolve the calcium out of your bones. I now use a product by ARCAIR, "Protex Alclean" Aluminum Cleaner, by Thermadyne. Many applications are reqyired. Wear old clothes, boots and glasses. Work outdoors. Don't breathe the fumes. Oddly it made my lawn grow REALLY WELL! This is an aluminum oxidation remover for welding.
 

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Paint can always be removed later, I suppose. I chose glass bead blasting to get my block looking original again. The oil-ways in my block have removable grub screws, so they could be cleaned after blasting.

How far is your mechanic with the bottom end rebuild? sacrificing a seal or two isn't a high price for a beautifully finished engine.

 

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I use a product called Aluma Bright sometimes to clean aluminum. It is fairly safe, and I wouldn't be afraid to clean it after assembly if your very careful. It takes several applications and a scrub brush to get things clean. See link below.

Jonathan

ALuma Brite
 

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Good info, and some very nice work in the pictures guys. Thanks for sharing.
 
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