Marccus
New Member
Here are some pictures I promised to show of my engine compartment after installing a rebuilt and painted intake manifold and valve covers:
1. Overall view of engine compartment
2., 3. High Gloss, High Temp (900F) Aircraft Engine Enamel.
To Paint Aluminum so it will not chip:
a. Clean the aluminum with phosphoric acid etch solution (AlumiPrep).
b. Rinse thoroughly and immediately coat the aluminum with a chromate conversion solution (Alodine).
Aluminum "rusts" immediately, but not like steel. Upon exposure to air the surface of Al forms an aluminum oxide layer AlO2, which is hard and won't crack.
When steel oxidizes (rust) it forms Fe2O3 which has a lower density than steel. So the rusted steel expands and chips away from the remaining steel and the process continues until the steel is gone.
If the density of rust were the same as steel then the surface coating on the steel would act exactly like the AlO2 coating on Al - a protective coating that prevents further oxidation taking place.
Unfortunately, steel got the bad deal.
Stainless steel is just that. It still rusts or "stains", but it stains "less" (!) than regular steel. The surface of stainless steel is protected by a coating when chromium is added to the steel. It is a chromium oxide coating like AlO2 on Al and won' expand and chip away - most of the time. The more chromium the less chance of staining.
But back to Al, the chromate conversion solution converts the AlO2 coating to a surface coating that binds to the paint stronger than the AlO2 coating.
So you can paint aluminum without it chipping or peeling but it is not as easily to paint as steel.
The other alternative of course is powder coating, but powder coating cannot easily be repaired if it chips.
zzzzzzzzzzzz So now that you are asleep and ready to delete this post, I'll point out several other things. zzzzzzzzzz
The gaskets in the manifold are a blue color; they are made of aramid fiber. Unfortunately you can't see them that well.
I didn't want to use paper gaskets, but wanted to use something more durable and had some "substance".
So I bought aramid fiber gasket sheets at McMaster-Carr and traced out new gaskets using the paper ones as a template.
Aramid fiber is pretty much impervious to everything and it came in the right thicknesses to match the paper gaskets.
The blue color is set off well with a nice contrast from the black manifold, throttle body.
You'll go through several Exacto knife blades trying to cut this stuff.
The 1/32" thickness is not too bad to cut, but the 1/16" is tough.
One thing I noticed about the paper gaskets on the runners is that they don't exactly match the openings, so there is some blockage.
I used a round and semi-round file to match the aramid fiber gaskets exactly to the size of the opening.
I did the stenciling by spending two hours a night over the course of three or four nights cutting out small pieces of masking tape (3M blue - very easy peel tape) and tweezers to outline the lettering.
Then I used silver aircraft engine enamel and sprayed the letters.
I won't do that again.
Very lastly, I don't know how to post images on this forum. I took the digital images at too high a resolution in camera I borrowed. Three pictures took up 16MB!! That's why they are so small, so as not to exceed the 37.5 KB per image.
But how do you attach more than three images in a post?
You see, I'm still a film guy - medium format (2 1/4") and 4x5 (head under the dark cloth) with wet chemistry although the advances in digital camera resolution and the quality of printing (inkjet, dye sub, etc) for black and white and color are simply amazing.
1. Overall view of engine compartment
2., 3. High Gloss, High Temp (900F) Aircraft Engine Enamel.
To Paint Aluminum so it will not chip:
a. Clean the aluminum with phosphoric acid etch solution (AlumiPrep).
b. Rinse thoroughly and immediately coat the aluminum with a chromate conversion solution (Alodine).
Aluminum "rusts" immediately, but not like steel. Upon exposure to air the surface of Al forms an aluminum oxide layer AlO2, which is hard and won't crack.
When steel oxidizes (rust) it forms Fe2O3 which has a lower density than steel. So the rusted steel expands and chips away from the remaining steel and the process continues until the steel is gone.
If the density of rust were the same as steel then the surface coating on the steel would act exactly like the AlO2 coating on Al - a protective coating that prevents further oxidation taking place.
Unfortunately, steel got the bad deal.
Stainless steel is just that. It still rusts or "stains", but it stains "less" (!) than regular steel. The surface of stainless steel is protected by a coating when chromium is added to the steel. It is a chromium oxide coating like AlO2 on Al and won' expand and chip away - most of the time. The more chromium the less chance of staining.
But back to Al, the chromate conversion solution converts the AlO2 coating to a surface coating that binds to the paint stronger than the AlO2 coating.
So you can paint aluminum without it chipping or peeling but it is not as easily to paint as steel.
The other alternative of course is powder coating, but powder coating cannot easily be repaired if it chips.
zzzzzzzzzzzz So now that you are asleep and ready to delete this post, I'll point out several other things. zzzzzzzzzz
The gaskets in the manifold are a blue color; they are made of aramid fiber. Unfortunately you can't see them that well.
I didn't want to use paper gaskets, but wanted to use something more durable and had some "substance".
So I bought aramid fiber gasket sheets at McMaster-Carr and traced out new gaskets using the paper ones as a template.
Aramid fiber is pretty much impervious to everything and it came in the right thicknesses to match the paper gaskets.
The blue color is set off well with a nice contrast from the black manifold, throttle body.
You'll go through several Exacto knife blades trying to cut this stuff.
The 1/32" thickness is not too bad to cut, but the 1/16" is tough.
One thing I noticed about the paper gaskets on the runners is that they don't exactly match the openings, so there is some blockage.
I used a round and semi-round file to match the aramid fiber gaskets exactly to the size of the opening.
I did the stenciling by spending two hours a night over the course of three or four nights cutting out small pieces of masking tape (3M blue - very easy peel tape) and tweezers to outline the lettering.
Then I used silver aircraft engine enamel and sprayed the letters.
I won't do that again.
Very lastly, I don't know how to post images on this forum. I took the digital images at too high a resolution in camera I borrowed. Three pictures took up 16MB!! That's why they are so small, so as not to exceed the 37.5 KB per image.
But how do you attach more than three images in a post?
You see, I'm still a film guy - medium format (2 1/4") and 4x5 (head under the dark cloth) with wet chemistry although the advances in digital camera resolution and the quality of printing (inkjet, dye sub, etc) for black and white and color are simply amazing.
