I'm not going to say it's a bad idea, but like Scott said you gotta watch where the water goes, and also I wouldn't do it with the engine hot. When I did mine a couple of weeks ago I covered my breathers, air filter, and coil pack but didn't think to cover the alternator and now I have a new one to install due to a squeaky bearing on the one that got wet.
Mike
1987 
GRAND NATIONAL
Many changes planned but for now it has:- TE44 turbo
- MSD 50 lb. injectors
- Turbo Tweak 93 octane street chip
- RJC Power Plate
- VDO boost gauge in pillar
- adjustable FP regulator
- Hotwired fuel pump
- Fuel pressure gauge
- 8" K&N cone filter
- ESP coil pack
- 160° thermostat
- test pipe w/ cutout
- Flowmaster exhaust
- Scanmaster 2.1