Cleaning out cylinder/Pistons..Lots of help

User the gasket scraper & finish it off by vacuuming the loose particles out and spraying it all down with WD40. Clean the WD40 off the head & block surfaces with some solvent or gas before you put the gaskets on.

Plan on changing the oil after 1-2 hours of run time. This will wash the loose dirt & gasket material down in the pan and allow it to be drained out when you change the oil.

Wait until you get the heads back on and running good to clean the engine. Then use some Gunk spray on engine cleaner & a high pressure sprayer like the one at the coin operated car wash. Works great as long as you don't spray the distributor too much.

i think a few more details would be helpful - is this an assembled shortblock - or is it dissasembled? I assume you are referring to a dissasembled motor. Carb cleaner - the type you buy in a bucket that is meant for soaking an entire carburetor - works well for loosening up the grime on the pistons. YOu can just strip the rings off and drop the whole rod/piston assembly in there. After that, a high pressure blast off will get a lot of crud off. After that, if you put the rod carefully in a vice, an old piston ring works very well for scraping off the carbon on the top of the piston. You can also use a broken ring to scrape the ring lands of the piston to get rid of all the carbon. As far as the block goes - just a good engine degreaser and a 3M scrubby pad will do wonders. You should probably wear gloves though - that stuff is nasty. I would follow up by washing the entire block VERY well with detergent and water.

If instead you are referring to an assembled shortblock just as you are swapping heads, any carbon you scrape off might find its way into the motor, and cause more problems than it solved. My .02 - hope this helps.