So last fall the neighbors 7.4L Merc is giving him some hard starting issues. So for shit's and giggles I pull his distributor cap and low and behold the rotor end and everyone of the distributor firing pins is corroded with that green build up scale. So we put a new cap and rotor in and change out all the spark plugs. Starting issue much better. So later this fall I'm changing my oil and filters and for shit's and giggles I decided to pull my distributor cap. Low and behold if my distributor cap and rotor looked as bad as the neighbors along with an accumulated amount of rust dust. So this spring I got new plugs, caps and rotors and went to work on my ignition system. The plugs appeared to all be burning perfect with a medium brown color on every spark plug I examined. Getting the rotors off the shafts was a chore, they had rusted on pretty good. I guess I hadn't noticed a starting issue in my case, though it did seem to take a little longer to fire up each time we went out. So I guess the marrow of the story is, take a look before its a real issue. Since I'm the 4th owner and found no service record of plugs, caps or rotors, for all I know they could have been originals! Question, the caps are I believe the HEI style and they had no gasket on them and the new ones I got had no gasket, but the neighbors cap did have and came with a gasket but yet had a moisture vent in the cap. Should these have a gasket or should we try to seal them with silicone or not? <Crusaders>