Some of you may remember my question regarding the gapping of three grounded Bosch plugs. I didn't get a definitive answer but a lot of speculation from brickboard. Some folks wanted to know as well, as they have seen them dropped and re-gapping was required. I know they are gapped at the factory, so some would suggest it is a moot point...on the other hand, it's good to check anyway. This is what I found out from a gentleman who works as part of the design team at Champion plugs. First and foremost (in his opinion) three grounded plugs and double electrode plugs are nothing more then marketing hype...three grounded plugs have been around since the forties, used in the aeronautical industry. Planes being what they are, every component has a redundant back-up. The plugs being no differant, in the event one prong got fouled, the other two would provide enough spark to ignite the fuel...but that's just it, three prongs are providing three weaker sparks, whereas a conventional plug with one ground prong generates one good healthy spark. So you decide...do you want one healthy spark, or three weaker ones seemingly backing each other up. As far as gapping goes, wire feelers are used and the distance between the ground tips and the electrode should all be of equal distance as specified by Volvo. I think it's 0.7-0.8...:) --
Tony G...'94 850GLT, '82 240DL (mint)