[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

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 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."