the important thing is to use new ignition components.a worn out cap and rotor will have a hard time keeping the engine running when everything is good and wet. quality plugwires are the most important thing. if your wires cross fire and arc,it will not run under water.
other than that,i don not really do anything special.i use dialectric grease in both ends of the plugwires,and in the cap on both ends of the rotor. i used to seal my cap to the distributor with gresae,but have found this to not really be neccessary. sealing the cap with silicone is even more of a waste of time,cause it will actually help retain the moisture,rather than allowing it to escape,and when you do have to take the cap off its a PITA to scrape off the old silicone.
the little flapper vlaves work ok,if theyre actually working,wich they prolly arent after 15+ years. i made a second sorklel to attach all vents for the tranny,axles,etc. make sure tha the vent on your motorcraft carb is run to somewhere where water wont get in it. i have heard of people ingesting water into their engines thru the charcoal canister,so dont assume thats a good place to leave it.
since you have an auto,its even more important to protect it. water and autos dont mix.there should be alittle pipe or something that you can put a hose on and run up high. go to yuor local gm dealer and buy a late model locking dipstick.it should fit your tube,you will have to cut it to lenght and scribe the full/add lines.i got the shortest one they had and it was still waaaaay to long [img]smile.gif[/img] it cost me all of 5 or 6 dollars.
another option is to use little filters on all of your breather vents. pep boys,and i think even the zone now sell a little tiny K&N type gauze filter that you can lube with K&N oil. i have been told that water cannot flow thru a properly oiled gauze filter.
keeping the intake air sealed with a snorkel is the next step. use a K&N filter in your air cleaner,and amke sure you plug up any sliitl places for water to seep in. i completely filled in the flapper valve on the bottom with silicone ,and reomved all the little fittings onthe sides of my stock air cleaner when i was still running it. you should be able to attach a stock air cleaner to PVC with a rubber 4" coupler,and a 4" to whatever size you want to run pvc reducer.i used to use clamps to keep the lid firmly attaced to the bottom.make sure that seal is in good shape,and lube it now and then with grease or vaseline.
last and not least,a mechanical fan is no good. if you want to play in deep water often,you need a clutch fan that will stop spinning,or an electric fan that you can turn off with a toggle switch. water has much more resistance that air,and it will put alot of strain on your engine to try and turn a mechanical fan(specially a big steel one-aluminum may flatten out) under water.
for the record,i have had my hood completley under water,and my engine still running. theres nothin funnerthan creek ridin on hot summer days
hope this helps. further questions? [img]smile.gif[/img]