I've found that common rubbing alcohol works great with a tooth brush if you don't let them get too far along.

Try to keep from using oven cleaners. Most will imediatly turn aluminum grey and even the aluminum safe ones will turn aluminum oxydized if left on the engine a long time.

Great Planes or Hobbico sell's a engine cleaner.

I'm thinking the one you want was marketed by Dave Gerieke?

Hot antifreeze in a warm crockpot works pretty well but you must remeove the engine from the plane.

Some people use carb cleaner from the auto parts store?

Enjoy,

Jim