I recently had my LT1 intake sandblasted and powedercoated. I spent a long time using compressed air to get everything out but everytime I shake it up more crap comes out of no where and I really have NO idea where it keeps coming from cause you cannot see well enough through any of the openings.

I need to get this on the car soon but am running out of ideas. Some of the material just looks like very tiny pieces of rust or something they are dark in color.

Any ideas on getting this all cleaned out better. I am going to try and use a block and hammer to knock some more stuff loose but dont know if that will get it all..

Take it to a shop that has a detergent power washer cabinet.

And keep in mind to never "sand" blast aluminum.
You should only media or bead blast it.

Before we profile blast (we use 70 grit A.O.) we always mask/seal any engine parts that have "blind" areas and will be exposed to the intake or oil areas of the engine.....also we chemicaly strip the majority of stuff and if the surface is rough enough to not need a profile blast that eleminates any contamination issues. I know it is to late for the OP to use this info but it might help someone else down the road to ask the coater what their process is before you decide to have them do your stuff. This is usally one of the differences between a good custom coating shop and an industrial coating shop.

Someguy, at this point I would continue to use air pressure untill nothing more comes out, then I would completely submerge the piece in a water (spin it around to get all air pockets out) then flush it with a pressure washer (using water only) followed with a pressurized air dry, that should take care of it.

Thanks, my next step was definitely to wash it out. I have a huge tupper ware container that I can use to submerge this thing... then I will wash it out and air dry and use the air compressor on again.

I put a wood block against the intake and hit it a few times with a hammer to knock stuff out and a TON of crap started to come out which I believe is from the media blasting (got the terminology right).

What are the 5 large threaded plugs in the bottom of the LT1 intake for? SHould I take those out to help flush the intake? I will need to go and get a hex head bit big enough to get it out.