cleaning aluminum intakes

[Belair62]

There ya go Frank...maybe it's not for you....

[CamarosRus]

...I had my 70 LT-1 manifold STEEL shot blasted(just like when they were mfg at the foundry) at a place that rebuilds Aluminum mostly japanese cylinder heads......not positive but a "Wheelabrator" brand or similar type of machine that they used to run heads thru on a conveyor belt like idea was used....They steel shot is only used on aluminum parts and wasnt contaminated with ferous metal or grease to get into or on intake or my Muncie case.....I'll attach several pics to show you examples of my intake, muncie case, AND muncie DIE-CAST PIECES which I had vibratory/tumbled in ceramic stones with a detergent/chemical cleaner.
I should probably retake these pics in higher resolution, but this all takes TIME......hope you get the idea.

Chuck Sharin Seattle

THE FOLLOWING IS A STATEMENT FROM JEFF BETZ WHO CURRENTLY IS AN ENGINEER WITH DAIMLER-CHRYSLER.....previously with G.M. Jeff supervises in the plant where misc Jeep engines are built.

"Guys, I'm a design engineer that has worked with many cast iron and aluminum parts, and sand cast parts DO NOT have any type of skin on them from the foundry. Chuck is exactly correct when he states a "Wheelabrator" brand cleaning process (or similar version) is used to clean the sand off of a cast aluminum part when it goes thru "shakeout" which is the process of removing the core sand and green sand from the casting process. The type of media used may vary among foundrys, but they are all cleaned using an abrasive. To duplicate the "as cast" aluminum intakes may be a trick, because we need to correctly match that intake as it came out of the shakeout line of the foundry. It's anybody's guess today as to what media was used, and I'm sure that varied from month to month and foundry to foundry.
DIE CAST aluminum parts are a different story. A die cast aluminum part gets it strength from the outer skin that forms against a permanent cooled mold, very different from the sand used in a sand casting that is recycled/trashed after each part. Transmission tail shafts and distributor housings are typical die cast parts. Today, some parts are a mix of a permanent external mold with internal sand cast cores."


[IMG]

[Salvatore]

Very nice stuff!

[SS427]

Something that works very well for me is I use glass media and then use a green Scotchbrite pad afterwards and put a very slight polish on in. Only the high points of the casting pimples get shined up. This has worked very well and resembles virgin castngs very closely.
Rick

[Salvatore]

Good idea Rick. I have a Z/28 intake that I will try it on. I feel alot of people mess their intakes and especially their valve covers up! Sam

[Charley Lillard]

Same process as Ricks only I use the green scotchbrite pad with warm water and dishwashing liquid.

[Belair62]

THAT's what I was talking about Chuck...steel shot..it make's it look brand new and no patterns...

[olredalert]

--Hey Chuck,

--------Is that Jeff Betz the same guy who just bought a 69 Chevelle wagon from some ol "tuna" up in East China Mi.? Sure sounds like the same guy. He and his Dad are both real nice people. I have heard from him that the 69 (a beautiful original car) will soon have substantially more power and a switch to 3 pedals. Hope we can get him interested in participating here on the board as his knowledge would be cool!........Bill S

[mrrec]

The GM engineer has some good info and I believe a good deal of it applies.

I own a small mfg co and have experience with new alum castings. Not all castings are media blasted, though, after shakeout (removal from the mold) and I don't know what they did in the musclecar era on trans parts and intakes. You can bet there is not one right answer!

Sand castings (intakes, trans main cases) are very bright (almost aluminum paint bright) as cast in many cases. You can duplicate this with an older casting (regardless if it has been blasted before) with a "brite dip" in acid. There are several formulations including 94% Phosphoric acid, 6% Nitric acid. I glass bead first, then dip. Contact time of the acid determines brightness. It works.

Die cast aluminum cannot have the original finish (skin) restored by media blasting. As cast, diecast has a much darker, smoother look. Once you blast it (vibratory, tumbling, media blasting), you're done. I have not found any procedure to accurately replicate this finish (just find a tailshaft housing someone hasn't messed with!).

The "reskinning" thing is a misnomer. You really can't "reskin" (and like the GM engineer said, sand cast aluminum doesn't have a skin anyway). I had McNeish do an intake to see what he was doing and it is appears to be just a media blast (media unkown). I've done the same with glass beads. It does look nice, though.

Cast iron "reskining" by those saying they do that is probably ceramic coating. Sand cast cast iron does have a bit of a darker colored "skin" in some cases. I had a set of exh manifolds for my Z16 ceramic coated in grey, then painted them Chev orange as proper. Hopefully, as the orange burns off over most of the body, they'll reveal the grey and stay that way.

Dave

[Charley Lillard]

Dave...For those of us who are now going out to look for Phosphoric and Nitric acids.... Where to get ? Dangers ? Did time suggestions ? Containers ? Disposal ? Shelf life ? Can we all send you our stuff ?