Hi Bill, Part of your post is misleading, at least the way I read it and I wanted to clarify something for those following this thread. A coil dose not store a charge like a capacitor. A large capacitor can store a charge (almost like a battery) and discharge even with the device turned off days weeks even months later. A coil does build up a magnetic field; it is when the power going to the coil is turned off that the coil creates High voltage by virtue of the magnetic field collapsing. This happens because a coil will resist an instantaneous change in current and when the current flow is stopped, the magnetic field collapses and tries to maintain current flow. The net result is that a voltage (a high voltage) is produced. Once the power is turned off to the coil and the field has collapsed (happens instantaneous for the purposes we are talking about, the coil is harmless (unlike a capacitor). Another thumb rule for sparking and arcing. 10,000 volts will jump about 1 inch at normal atmospheric pressure. The one inch rule has many variables and inside the combustion chamber of an engine has very little to do with what happens outside at atmospheric pressure but I thought it was an interesting bit of trivia. One other thing and I'm not picking on you if it is a typo. When you refer to HT are you referring to HV for high voltage? If not pleas let me know what HT is. Regards, Mike D. > Plug gap has absolutely no bearing on coil output. Is going to build > up HT even if never grounded (that's why you have to be careful > grabbing distributor lead wire even after ignition turned off -- if > last plug never fired YOU'LL become the ground). Gap has everything to > do with flame propogation, and ability of HT to jump (too big gap with > too low voltage won't fire). > > Bill Robertson > #5939 > > >--- In dmcnews@xxxxxxxxxxxxxxx, "Elvis Nocita" <elvisnocita@xxxx> wrote: > > > > I still don't get you guys with that high voltage stuff. > > Tha max-voltage on the plugs depends of the gap (and the mixture). > > > My 2 cents, and my book about car electrics and stuff proves me > right.... > > > > Elvis & 6548