Spray on a cleaner of some type being cautious of what Im spraying (Not good for rubber etc..)
Then I use a low pressure water spray to rinse it off.
**NOW** On the LT1 you want to be careful not to hit the optispark (Your distributer) I guess this causes all types of problems. Just follow the spark plug wires to find it. Then simply stay away from it.
After Im done spraying (If bad enough) I turn it on high pressure to clean the under side of the hood and top end of the motor. (Do your suspension while your in there.)
Then I take clean shammy's/rag's and wipe down whatever I need to. Sometimes I use a Meguiars rubber finisher to bring back the rubber, black plastic's, and wires
You'll look like new after that (actually better than new)
I DID IT ONE TIME TO MY 94', IT BACKFIRED AND BARELY RAN FOR ABOUT 5 MILES. IT SCARED THE **** OUT OF ME. IF YOU STILL WANT TO WASH THE ENGINE WRAP THE OPTI SPARK IN A PLASTIC BAG AND PUT A RAG AROUND IT. BE VERY CAREFULL.
ANOTHER GREAT ENGINEERING MARVEL. IT IS ALSO LOCATED UNDER THE WATER-PUMP. WHEN THE WATER-PUMP GOES IT CAN DRAINS ALL OVER THE OPTI-SPARK AND CAN CAUSE DAMIAGE TO THE OPTI-SPARK UNIT. I HEARD THEY IMPROVED IT ON THE 95/96 MODELS. I NOW HAVE A 95 AND LOVE IT.
I have 4 cars, two Vettes, a Windstar and a restored '55 Chevy with a 350 in it. (okay, restored "street"!)
I wash them all regularly at the car wash which has a high pressure hose, etc. I never use the high pressure but I do use their engine detergent and hot water.
I have never ever had a problem with any of them and I have been doing this for more years that I want to admit to. If a problem does occur then someting is not quite right.
I do stay away from the distributors (Or coil pack on the WS) and the carb on the '55 with the water stream. Actually I stuff a shop towel into the 4 barrel and wash the carb itself quite well.
Okay, I worry less about water problems (since I have never had one) then I do about a dirty engine.