GM's Top Engine Cleaner works well. You pour it down the carb in a small
stream with
the engine running and then dump the last bit in all at once and stall the
engine.
You let it sit for a while and then start it back up. You should see lotsa
black
coming out the exhaust if you have a lot of carbon build up. I suppose you
could
use it on a disassembled engine. Water, which is cheaper ) works almost as
good.
A trickle from your garden hose down the carburetor whilst the engine is
running.
(you'll have to manually work the throttle to keep it running)

As for something that works with the heads off of the car, regular spray
type carburetor cleaner
probably works fairly well. Maybe that was what was being used. Most heavy
crusty carbon needs
a bit of scraping no matter what.

>>>Mike