[82 Silverado 4X]

Just a quick note to this post.
I saw that many suggestions were given and all were sound, but no one mentioned that GUNK Engine Degreaser is flammable. If you plan on using it or any other kind of engine cleaner read the can.
Don't spray it on a running engine and don't try to start the engine until the engine cleaner has been sprayed off.
I almost lost a 71 Fiat to this error in judgement.