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I have this ...490 intake in the basement and I am puzzled by the roughness of the casting. The t-stat area is intact but overall the surface of the intake is pretty crude. The head mating surfaces are clean and true. Is this roughness a characteristic of the breed or is this intake a victim of surface corrosion?
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Re: C2 ...490 Intake Casting Roughness/Pitting
From what I can tell from the photograph, the surface is typical factory production. Sand casting, no attempt to polish.
If it flowed air and fuel, didn't leak oil or water, and sealed against the cylinder heads, it was installed.Dick Whittington -
Re: C2 ...490 Intake Casting Roughness/Pitting
Paul,
The surface texture appears to be typical, but it looks like it has been painted. It seems too reflective and there is a trace of paint the bottom of carb stud.
I think you might loose points if it is painted. Maybe you don't care.
If you want to remove the paint, you can use aircraft paint stripper (available at pep boys) with a lacquer thinner "wash down" using a stiff paint brush. This stuff is safe for aluminum as most aircraft skins are aluminum.
Do not use a wire brush or bead blaster.
tcComment
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Re: C2 ...490 Intake Casting Roughness/Pitting
Paul-----
I agree, too; it's a VERY normal surface texture. All Corvette intake manifolds, cast iron or aluminum for all model years 1953 through 1996, were sand castings. Sand castings always exhibit a rough surface texture due to the "texture" of the sand.
Permanent mold or die cast aluminum parts (like 63+ bellhousings) are smooth. But, NO Corvette intake manifold was ever made of such a casting-type.In Appreciation of John HinckleyComment
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Re: C2 ...490 Intake Casting Roughness/Pitting
My thanks to all! I have been working on this one for several days and suddenly twigged to the rough casting texture. But it is straight and true. Yes it has been painted with some form of intake paint. Here it is with a wrong t-stat housing as a mock-up to get the right bolt sizes. I can strip it off with lacquer thinner if need be but would prefer to get some type of paint on it. This is a winter project so no rush.Comment
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Re: C2 ...490 Intake Casting Roughness/Pitting
Paul-----
Many original GM aluminum intake manifolds were painted with aluminum paint from the factory. I don't know if this was done on the manifolds prior to their arrival at the engine assembly plant, after any machining done at the engine plant, or at the same time that the rest of the engine was painted. I tend to think that it likley was done at the same time, or immediately subsequent to, the painting of the rest of the engine. I think that it was likely done to ensure that "stains" which might have occurred during the engine assembly process were "covered up and looking pretty" prior to the engine's shipment from the plant.In Appreciation of John HinckleyComment
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Re: C2 ...490 Intake Casting Roughness/Pitting
I no longer have my 66 L79 but, IIRC, all aluminum intakes were painted silver and are judged accordingly. Anyone with a current 66 JG?
GaryComment
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Re: C2 ...490 Intake Casting Roughness/Pitting
I will leave the paint on but try to dull it out a little bit.Comment
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The '66 JG says ...
"L79 350 hp intake manifolds are aluminum and may show a light spray of silver paint on the sides and organe overspray at the front or rear edges where they meet the block."
GBComment
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Re: The '66 JG says ...
And the '67 JG sez, for the same intake, that it's painted; go figureComment
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Re: C2 ...490 Intake Casting Roughness/Pitting
This is for Joe Lucia:
Joe, was this aluminum intake painting phenomenon:
1) A small block oddity, or big block as well?
2) Only utilized in 66 & 67 Corvettes?
3) Used on other applications ( Camaro, Chevelle, Nova, etc.. )
When this practice cease?
SteveComment
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