Well, I saw this written up in the Dec. MA so I thought I'd give it a try. I had a twenty year old FP .40 around that had been rebuilt a couple of times that was pretty kruddy. I don't clean a whole bunch of engines so I haven't been willing to invest in a crock pot set up.
First of all I had a hard time finding the DAWN POWER DISOLVER. It is supposed to be carried in the super markets with other DAWN products. Not in Publix, or Sweetbay (Florida) stores. Finally got some at Albertsons. About 3 dollars and change. Cheap, if it works!
Welllllll...Yes it did get most of the burned gunk off after an hour of squirting and soaking and scrubbing with a stiff tooth brush. It did need a second bath to get it all off. It didn't get the burned oil stains off that gather around the exhaust stack and the muffler. It also darkened the cleaner areas of the engine and left some black splotches behind.
If your need is to get caked gunk off your engines, this will work. But if you want to get your engines pretty again, I can't recommend POWER DISOLVER.