Do you mean cleaning, or do you mean plating, and swapping out rusted parts, clamps, nuts, bolts, screws, also repaint? If just to clean, power wash with Gunk to remove grease, oil, etc. Clean engine bay and engine with Gunk. Replace all rubber hoses, belts and seals, replace clamps, screws, bolts that are rusted, paint engine block (black) and replace any part under the hood that is rusted or discolored. Is this what you mean by detailing?
Bob